# Difference between revisions of "pm39 interface analysis"

## Introduction

Note: this is very much a first and working draft!

This analysis of the ConTeXt interface is an effort to understand how different kinds of commands are expressed, to help support the effort of generated a DITA document set.

I used the interface file context-en.xml:

file name
context-en.xml
date collected
2020-06-27
size
1685184
md5
48edfd4fb6e71aee7a49023f0527a461

I used xmlstarlet:

   http://xmlstar.sourceforge.net


...to gather and process most of data from context-en.xml; for the queries that required XPath 2.0+ features, I used Xmplify.app.

## Vocabulary and Other Assumptions

The interface file is made up of a number of cd:interface elements that describe a hierarchy based on source files.

Inside this hierarchy of interface elements are a set of cd:command elements. I'm going to refer to these elements as stanzas.

Some commands are instances of a more general idea of functionality. I'm going to refer to the parent elements of instances as classes.

Each stanza can refer to one of a number of different kinds of entities:

• a command
• a paired command, which describes the start and stop commands for a section
• a class, with enumerated instances of that class that are available by default as part of the distribution
 NOTE: fourth option: an example (dummy) of a potential generated instance. these are the ones with variant=example*

Commands may or may not also be indicated as environments, which describe a set of generated commands.

 NOTE: this is the same as a 'paired command'.

There are 4028 stanzas in the interface file, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command)' context-en.xml


## Attributes Used in The Root Element of a Stanza

Root elements of a stanza can have one of several available attributes. The patterns of some of these attributes give hints to the function or purpose of the stanza.

From the following XPath expression:

distinct-values(//cd:interface/cd:interface/cd:command/@*/name())


...we have a list of 11 attributes found attached to root elements of stanzas in the interface:

• file
• level
• name
• category
• type
• variant
• generated
• begin
• end
• scope
• coreprimitive

(Note that we also appear to have two misspellings of "category"; see #misspelled_category)

### The file Attribute

The file attribute specifies the source file that defines the command.

4027 stanzas have the file attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@file])' context-en.xml


One command does not have the file attribuite, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v '//cd:interface/cd:interface/cd:command[not(@file)]/@name' context-en.xml


... is: doifelseframed.

### The level Attribute

The value of the level attribute loosely specifies how the command is part of the typesetting system.

The level attribute has three possible values in the interface:

• style
• document
• system

Commands with a level of style or document are expected to be used by people using ConTeXt to prepare documents; commands with the level of system are internal commands with an expected audience of programmers and implementors who need to know about ConTeXt internals.

4025 stanzas have the level attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@level])' context-en.xml


The three commands that do not have the level attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v '//cd:interface/cd:interface/cd:command[not(@level)]/@name' context-en.xml


...are setupoutput, postponingnotes, and script.

### The name Attribute

The name attribute specifies the name associated with the stanza, and may refer to a command, a stem for a command pair or environment, or a class.

4028 stanzas have this attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@name])' context-en.xml


There is no stanza in the interface without this attribute in its root element.

### The category Attribute

The category attribute specifies the category (or categories?) assigned to a given stanza.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/@category)


...there are 79 discrete values for categories used in the interface:

• mathematics
• alignment
• attribute
• background
• background colors
• background conditional
• rules
• rules colors
• graphics
• structure
• pdf
• conditional
• buffer conditional
• buffer
• buffer lua
• buffer verbatim
• fonts
• catcode
• characters
• characters fonts
• language
• colors
• colors conditional
• tables
• float tables
• counter
• counter language
• counter conditional
• system
• language alignment
• fonts colors
• xml
• pdf conditional
• pdf background rules
• pdf background
• structure conditional
• structure lua
• structure conditional xml
• rules metapost
• background layout
• background layout metapost
• structure fonts counter
• structure background
• structure counter
• fonts conditional
• background rules
• background rules mathematics
• graphics conditional
• graphics buffer
• graphics structure
• layout
• whitespace
• whitespace layout
• symbols
• fonts whitespace
• language conditional
• background metapost
• layout conditional
• tables buffer
• lua
• structure layout
• mathematics alignment
• mathematics tables
• graphics metapost
• graphics metapost fonts
• graphics metapost conditional
• structure notes
• structure notes conditional
• background fonts colors
• bibliography
• bibliography conditional
• references
• references conditional
• symbols conditional
• symbols graphics
• xml conditional
• xml language
• verbatim
• verbatim conditional

....although if these are space-separated, there is overlap.

Note: this analysis does not include stanzas with misspelled category attributes.

Note for the DITA rendering of the interface: if these are space separated, they can be parsed out into separate category elements.

 NOTE: I always thought these were full strings, but you could be right about space separation

### The type Attribute

At the root level of a stanza, the type attribute can indicate the type of the stanza.

369 stanzas have the type attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@type])' context-en.xml


It does not appear that this is a required attribute.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/@type)


At the root level of the stanza, the type element has one possible value:

• environment

This attribute is significant for indicating this stanza describes an environment.

### The variant Attribute

The variant attribute specifies more information about the type of the stanza, and may be used to disambiguate stanzas.

3299 stanzas have the variant attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@variant])' context-en.xml


It does not appear that this is a required attribute.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/@variant)


...31 discrete values are used in the interface for the variant attribute:

• argument
• instance
• example
• page
• list
• direct
• button
• name
• 1
• 2
• 3
• matrix
• example:title
• string
• preset
• command
• assignment
• item
• symbol
• none
• combination
• instance:assignment
• collector
• layer
• userdata
• alternative
• instance:ownnumber
• instance:argument
• angles
• example:angles

A value of instance is important for interpreting the kind of stanza.

 NOTE: AFAICT, the values are CDATA on the xml level. In general, they are there to allow for a unique stanza in cases where not all calling conventions can be expressed in a single stanza. The two exceptions are the CDATA values prefixed with instance and example. The example cases are when there is the potential for a command instance, but there are no predefined instances in the actual distribution. The instance indicates cases where there are predefined instances. Processing note: I do not trust the instance prefix in my processing, I check for the existence of  children in the  child tag. However, I am not sure if this is needed. I have not run tests on the XML to verify that the prefix instance and child  always exist together, I just assumed that testing in actual instances was better than relying on a CDATA argument value

### The generated Attribute

The generated attribute indicates if the stanza is describing a set of commands.

 NOTE: not necessarily a set of commands, it could be a single command (or environment)

138 stanzas have the generated attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@generated])' context-en.xml


It does not appear that this is a required attribute.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/@generated)


...the generated element has one possible value:

• yes

This attribute is significant for indicating this stanza describes a generated command.

### The begin and end Attributes

The begin and end attributes indicate the strings that must be prepended to the command stem to create the command pair.

41 stanzas have both begin and end attributes, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@begin and @end])' context-en.xml


(This is also the number of stanzas that have either of these attributes.)

It does not appear that these are required attributes.

 NOTE: they have default values of start and stop, and are only relevant for stanzas with type=environment

### The scope Attribute

I am not sure what the scope attribute indicates.

 NOTE: scoped commands are only defined 'meaningfully' inside specific environments. For example, \item only works properly inside of commands defined by \defineitemgroup.

10 stanzas have the scope attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@scope])' context-en.xml


As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/@scope)


...the scope element has two possible values:

• formula
• itemgroup
 NOTE: the possible value list may grow in the future? It could be that some of the row/cell commands in some of the table environments only meaningfully exist within their table environments. Also, there may appear new commands in the future that have a specific scope

It does not appear that this is a required attribute.

### The coreprimitive Attribute

I am not sure what the coreprimitive attribute indicates.

 NOTE: Neither am I. Perhaps this is a new idea?

3 stanzas have the coreprimitive attribute, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command[@coreprimitive])' context-en.xml


As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/@coreprimitive)


...the coreprimitive element has one possible value:

• yes

It does not appear that this is a required attribute.

## Structures

This section is incomplete: I am focusing on element structures that will help parse the interface file into the DITA documentation set.

According to the Xpath expression:

count(//cd:interface/cd:interface/cd:command/*/name(.))


3560 of the stanzas contain more structure, with details about the command or class.

According to the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/*/name(.))


...these stanzas with interior structure have at least one of the following child elements:

• cd:arguments
• cd:sequence
• cd:instances

### Arguments

Stanzas may have an cd:arguments substructure, to describe command arguments.

As reported by the Xpath expression:

count(//cd:interface/cd:interface/cd:command/cd:arguments/@*/name(.))


....no cd:argument elements have attributes.

3333 stanzas have an arguments substructure, as reported by:

xml sel -N cd=http://www.pragma-ade.nl/commands -t -v 'count(//cd:interface/cd:interface/cd:command/cd:arguments)' context-en.xml


As reported by the Xpath Expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/*/name(.))


...argument structures support the following child elements:

cd:keywords
Setups of options - keywords separated by a comma.
cd:assignments
Setups of settings - key=value pairs, separated by a comma.
cd:csname
A ConTeXt command name.
cd:content
Mixed content?
 NOTE: I would define this as 'generic content'
cd:delimiter
A piece of text (a command?) that is used to mark arguments.
 NOTE: Yes, a command. The name attribute gives the command name. These are literal required commands that are used as argument separators.
cd:dimension
A quantity of linear measure.
cd:triplet
A description of a color.
cd:position
(unknown)
 NOTE: positions are an old subsystem for absolute placement that is not used a lot, since it has since been superseded by layers and overlays. you'll have to look at pack-pos.mkiv to get an idea for how it works.
cd:index
(unknown)
 NOTE: this is a list index entries. They are mentioned separately because index entries have a sub-syntax of their own
cd:text
(unknown)
 NOTE: Generic horizontal mode content. The sole occurrence of this is in \setwidthof.
cd:apply
(unknown)
 NOTE: these are apply lists, which define jump tables. Syntactically, apply lists are like key=value lists, except they use => as separator instead of =. Have a look at the System_Macros/Action_Processing page for more details.
cd:template
(unknown)
 NOTE: table column definition templates, like for \starttable[ 
cd:angles
(unknown)
 NOTE: \type and \typ also allow a call with double angle brackets, like this: \type>
cd:string
(unknown)
 NOTE: an argument that is explicitly a bare string, for string comparisons

#### cd:keywords

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:keywords/@*/name())


...cd:keywords elements accept the following attributes:

delimiters
The type of delimiters requested for the argument. Values found in the interface are none, braces ({}), and parenthesis. Square brackets ([]) are the implied default?
 NOTE: yes, square brackets default
list
?
 NOTE: list=yes means this is defines a comma-separated list. if missing, this defines a single keyword option
optional
The argument is optional.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:keywords/*/name(.))


...a cd:keywords element can contain one or more cd:constant elements and/or cd:inherit elements.

The cd:constant element defines a single keyword.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:keywords/cd:constant/@*/name())


...can have four possible attributes:

type
The label or name of the option.
default
Whether ("yes") or not this constant is a default.
method
?
prefix
?
 NOTE: This one I am not quite sure about, but I interpret method, prefix and type like this: method=range the argument is specified as prefix, followed by :, followed by type method=apply the argument is specified as prefix, followed by ->, followed by type method=factor the argument is specified as prefix, followed by *, followed by type method=none the argument is specified as prefix, followed by type The values of both prefix and type can be one of the predefined cd:XXXXX value types, or a literal string like * or all. A useful example is in Command/setupreferencestructureprefix

The cd:inherit element acts as a pointer to the options of a donor command by command name. The cd:inherit element uses the name attribute to indicate the donor command.

#### cd:assignments

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:assignments/@*/name())


...cd:assignments elements accept the following attributes:

delimiters
The type of delimiters requested for the argument. Values found in the interface are none, braces ({}), and parenthesis. Square brackets ([]) are the implied default?
list
?
 NOTE: list=yes means this is defines a comma-separated list. if missing, this defines a single key-value option (which I think never actually happens)
optional
The argument is optional.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:assignments/*/name(.))


...a cd:assignments element can contain one or more cd:parameter elements and/or cd:inherit elements.

A cd:inherit element at this level acts as a pointer to the settings of a donor command by command name. The cd:inherit element uses the name attribute to indicate the donor command.

The cd:parameter element defines the structure of a key and associated values.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:assignments/cd:parameter/@*/name())


...a cd:parameter element can accept two attributes:

name
The name of the key in the key=value pair.
list
?
 NOTE: list=yes means this is defines a comma-separated list. if missing, this defines a single parameter

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:assignments/cd:parameter/*/name(.))


...a cd:parameter element can contain one or more cd:constant elements and/or cd:inherit elements.

The cd:constant element defines a single keyword.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:arguments/cd:assignments/cd:parameter/cd:constant/@*/name())


...can have four possible attributes:

type
The label or name of the option.
default
Whether ("yes") or not this constant is a default.
method
?
prefix
?
 NOTE: see above for method/prefix/type

(Note: there is one instance of a possible type on Line 38818: <cd:constant defult="yes" type="stop"/> )

A cd:inherit element at this level acts as a pointer to the options of a donor command by command name. The options of the donor command are used as values for the associated key. The cd:inherit element uses the name attribute to indicate the donor command.

### Sequence

Stanzas may have an cd:sequence substructure, to describe command arguments.

As reported by the Xpath expression:

count(//cd:interface/cd:interface/cd:command/cd:sequence/@*/name(.))


....no cd:sequence elements have attributes.

As reported by the Xpath expression:

distinct-values(//cd:interface/cd:interface/cd:command/cd:sequence/*/name(.))


...sequence elements can contain the following child elements:

• cd:instance
• cd:variable
• cd:string

#### cd:instance

As reported by the Xpath expression:

count(//cd:interface/cd:interface/cd:command/cd:sequence/cd:instance)


...91 sequence substructures have an instance child.

As reported by the Xpath expression:

//cd:interface/cd:interface/cd:command[@variant="instance"]/cd:sequence/cd:instance


....84 of these stanzas have the variant attribute set to instance in the command element.

Having a combination of an cd:instance element and variant="instance" attribute strongly correlates with the stanza describing a class.

The cd:instance element carries an attribute of value, which maps to the replaceable stem of the class.

NOTE: Based on email exchange with Wolfgang:

#### instance generators

instances are generated by a generator command. Currently, I find the generator command as follows:

• take the value of the name attribute at the top level of the stanza
• prepend define
• look for a replacement in the following table
  local corrections = {
definefloats = 'definefloat',
definebox = 'definehbox',
definectxfunction = 'installctxfunction',
definectxfunctiondefinition =  'startctxfunctiondefintion',
definefence = 'definemathfence',
definelabel = 'definelabelclass',
definelanguage = 'installlanguage',
definesynonym = 'definesynonyms',
definesorts = 'definesorting',
}

• the result is the generator command for all the instances in the stanza

#### cd:variable

(I'm not sure what this is meant to indicate, but it seems to correlate with examples? -pm39)

 NOTE: my guess is that these are leftovers. But see also the discussion about variant=example on the wiki mailing list

#### cd:string

The cd:string element indicates a piece of text that is a particle of the command name of an instance, and is appended to the stem to create the full command name of an instance.

cd:sequence elements can have zero, one, or two cd:string elements. Up to one cd:string element can appear either before or after the cd:instance element.

The cd:string element carries an attribute of value, which maps to the affix text that should be added to command name for instances of the class. The string is added in prefix or postfix depending on where the cd:string element is ordered within the cd:sequence element.

### Instances

The cd:instances element contains one or more cd:constant elements, each of which describes an instance of the class named by the stanza. The stem values of the instances are indicated by the value attribute.

## Kinds of Stanzas

The purpose of this analysis is to help support automatic translation of the ConTeXt interface files into a topic-based DITA documentation set. As a result, it appears the ConTeXt interface stanzas describe at least two, and possible three, different things., and an additional feature axis.

### Command Stanzas

Some stanzas describe commands.

This can be straightforward, with a one to one relationship between the stanza and a command.

As my sample cases for this kind of stanza, I have the \inhibitblank stanza and the \blank stanza.

Some command stanzas describe pairs of commands; using begin and end attributes to indicate prefixes, these stanzas explicitly describe commands which bracket content. The contents of cd:argument, if extant, only apply to the command with the begin prefix.

As my sample case for this kind of stanza, I have the TD stanza.

#### \inhibitblank

The \inhibitblank stanza looks like this:

<cd:command category="whitespace" file="spac-ver.mkiv" level="system" name="inhibitblank"/>


This stanza has no internal structure.

This stanza is not:

• An environment.
• A variant.
• Generated.

#### \blank

The \blank stanza looks like this:

 <cd:command category="whitespace" file="spac-ver.mkiv" level="document" name="blank">
<cd:arguments>
<cd:keywords list="yes" optional="yes">
<cd:constant type="preference"/>
<cd:constant type="samepage"/>
<!-- cd:constant elements removed for clarity -->

<cd:constant type="cd:dimension"/>
<cd:constant type="cd:name"/>
</cd:keywords>
</cd:arguments>
</cd:command>


This stanza has internal structure: a argument of type options, with a list of available keywords.

This stanza is not:

• An environment.
• A variant.
• Generated.

#### TD

The TD stanza looks like this:

<cd:command begin="b" category="tables" end="e" file="tabl-ntb.mkxl" level="document" name="TD" type="environment">
<cd:arguments>
<cd:assignments list="yes" optional="yes">
<cd:parameter name="nx">
<cd:constant type="cd:number"/>
</cd:parameter>
<!-- cd:parameter elements removed for clarity -->

<cd:parameter name="action">
<cd:constant type="cd:reference"/>
</cd:parameter>
<cd:inherit name="setupTABLE"/>
</cd:assignments>
</cd:arguments>
</cd:command>


This stanza has internal structure: a argument of type settings, with a list of available keys and values for each key.

This stanza is:

• An environment.

This stanza is not:

• A variant.
• Generated.

### Class Stanzas

Some stanzas describe classes.

These stanzas describe a series of instances of the class; a series of commands that share the class' setups and details.

Instances that are offered as part of the standard distribution are captured as a series of chile cd:constant elements, with the instance name expressed as the value associated with the value attribute of the cd:constant element.

Classes imply that the user may generate their own instances, creating specialized instances of the class with the appropriate \definestem command.

 NOTE: see above for special cases of generator commands that are not exactly \definestem

As my sample case for this kind of stanza, I have the \itemgroup stanza.

There are two stanzas with the name itemgroup.

The first stanza for name="itemgroup" looks like this:

  <cd:command category="structure" file="strc-itm.mkvi" generated="yes" level="document" name="itemgroup" type="environment" variant="instance">
<cd:sequence>
<cd:instance value="itemgroup"/>
</cd:sequence>
<cd:arguments>
<cd:keywords list="yes" optional="yes">
<cd:inherit name="setupitemgroup"/>
</cd:keywords>
<cd:assignments list="yes" optional="yes">
<cd:inherit name="setupitemgroup"/>
</cd:assignments>
</cd:arguments>
<cd:instances>
<cd:constant value="itemize"/>
</cd:instances>
</cd:command>


This stanza has the attribute and value of generated="yes". This implies that the commands are created automatically as part of the standard distribution.

This stanza also has the attribute and value of variant="instance", and has a cd:instances element with more than zero child elements. This implies that this stanza describes a class.

The second stanza for name="itemgroup" looks like this:

  <cd:command category="structure" file="strc-itm.mkvi" level="document" name="itemgroup" type="environment">
<cd:arguments>
<cd:keywords>
<cd:constant type="cd:name"/>
</cd:keywords>
<cd:keywords list="yes" optional="yes">
<cd:inherit name="setupitemgroup"/>
</cd:keywords>
<cd:assignments list="yes" optional="yes">
<cd:inherit name="setupitemgroup"/>
</cd:assignments>
</cd:arguments>
</cd:command>


The second stanza describes a simple itemgroup command, with an environment.

### Example Stanzas

I'm not sure how the example stanzas work, yet. From the label, I expect them to be more towards documentation than implementation, but I don't know.

 NOTE: Example stanzas are for instances that could be generated, but of which there are no examples in the ConTeXt distribution. description and effect are good examples of this type of stanza. While there are the associated commands \definedescription and \defineeffect, ConTeXt itself never bothers to the define any instances

### Environments

Stanzas can have an additional intrinsic of describing an environment, indicated by the type attribute having the value environment.

I believe this creates a family of related commands around the environment:

• \startstem
• \stopstem
• \setupstem

...and possibly others.

 NOTE: the existence of \setupstem is not a given, but yes there could be others as well. Many of these commands are created by some code that is embedded in the \defineXXX generated by \installcommandhandler, but environments can also be created 'manually' by a pair of \def commands, like for example the \startluacode environment. The only guaranteed defined commands for any environment is the pair of start/stop commands

An environment does not necessarily create the command:

• \stem

...but I'm not sure if it never does.

 NOTE: Hans is quite meticulous in creating these standalones even in the manual generation cases if it makes sense to have that standalone command, but some them are missing for sure, e.g. \buffer

## Results

If we want to use the interface file to build a complete command set, the procedure is:

1. Does the stanza describe a class?
• Is the variant="instance" attribute extant (with the value instance)?
• Does the stanza have a cd:instances element, with non-zero children?
2. Does the stanza describe a pair?
• Is either or both of the begin= or end= attributes extant? (Hopefully both!)
 NOTE: should be both or neither, I assume. But whether it is an environment is decided by type=environment
1. Does the stanza describe a command?
• Does the stanza not describe a class?
• Does the stanza not describe a pair?
• Does the stanza not have a variant attribute?

Orthogonal to this, a stanza may describe an environment, if the type="environment" attribute is extant (with the value environment). This implied further automatically generated commands based ont he command stem, but interactions with commands, pairs, and classes is unclear.

 NOTE: begin and end are nothing but overrides for the implied values start and stop

## Things to Ponder

### What does an environment imply for command generation?

What commands are available as a result of an environment?

 NOTE: only the \start and \stop are guaranteed (but perhaps with different prefixes cf begin and end attributes.)

### What does a class imply for command generation?

Does a class generate just the commands described by the children of the cd:instances element?

(Experience with \bar implies yes: the literal command \bar relates to mathematics, while the instances of the \bar class are a series of prefix + stem command names.)

 NOTE: yes, I firmly believe you are right

### Expanding the Element Vocabulary?

Given that the stanzas are describing different things, it may be worth the effort to expand the element vocabulary for the stanzas.

• command

....elements, it may make sense to describe stanzas with the following elements:

• command
• class

...and possibly:

• example

A further disambiguation that might be useful is the addition of:

• pair

...elements, to explicitly mark elements that generate commands with prefixes and stems.

 NOTE: I have missed something somewhere, because this remark is unclear to me.
 NOTE: This may or may not be what you're asking: Instead of having every stanza be represented by a element, instead do (taking your notes into consideration): (Describes a command) (describes a class) (describes an environment, with or without overrides) ...? This way, the thing being described by the stanza is explicit...
Right, I see. I certainly would not mind, but it will depend on Wolfgang (who is the actual maintainer) and Hans (who is using the xml files for various distribution-related things Taco (talk) 16:15, 30 June 2020 (CEST)

## Apendicies

### Attributes that are Likely Misspellings of "category"

catehory
Line 861 - <cd:command catehory="pdf" file="back-ini.mkiv" level="style" name="setupbackend">
Line 3361 - <cd:command catehory="pdf" file="scrn-but.mkvi" level="style" name="definebutton">
Line 3374 - <cd:command catehory="pdf" file="scrn-but.mkvi" level="style" name="setupbutton">
Line 3409 - <cd:command catehory="pdf" file="scrn-but.mkvi" generated="yes" level="document" name="button" variant="example">
Line 3428 - <cd:command catehory="pdf" file="scrn-but.mkvi" level="document" name="button">
Line 3441 - <cd:command catehory="pdf" file="scrn-but.mkvi" level="style" name="overlaybutton">
Line 3448 - <cd:command catehory="pdf" file="scrn-but.mkvi" level="style" name="overlaybutton" variant="direct">
Line 3455 - <cd:command catehory="pdf" file="scrn-but.mkvi" level="style" name="MPmenubuttons">
Line 3462 - <cd:command catehory="pdf" file="scrn-fld.mkvi" level="style" name="overlayrollbutton">
Line 3472 - <cd:command catehory="pdf" file="scrn-fld.mkvi" level="style" name="definepushbutton">
Line 3482 - <cd:command catehory="pdf" file="scrn-fld.mkvi" level="style" name="pushbutton">
Line 3492 - <cd:command catehory="pdf" file="scrn-fld.mkvi" level="style" name="definepushsymbol">
Line 3504 - <cd:command catehory="pdf" file="scrn-fld.mkvi" level="style" name="rollbutton" variant="interactionmenu">
Line 3520 - <cd:command catehory="pdf" file="scrn-fld.mkvi" level="style" name="rollbutton" variant="button">
catgeory
Line 19207 - <cd:command catgeory="fonts whitespace" file="typo-pnc.mkic" level="style" name="defineperiodkerning">
Line 19220 - <cd:command catgeory="fonts whitespace" file="typo-pnc.mkic" level="style" name="setupperiodkerning">
Line 19232 - <cd:command catgeory="fonts whitespace" file="typo-pnc.mkic" level="style" name="setperiodkerning">
Line 19240 - <cd:command catgeory="fonts whitespace" file="typo-pnc.mkic" level="style" name="resetperiodkerning"/>

### Attributes that are Likely Misspellings of "default"

Line 38818: <cd:constant defult="yes" type="stop"/>

### Missing "file" attribute

Line 14799 - <cd:command category="background rules" level="system" name="doifelseframed">

### Missing "level" attribute

Line 934 - <cd:command file="back-ini.mkxl" name="setupoutput">
Line 27165 - <cd:command category="structure notes" file="strc-not.mkvi" name="postponingnotes" type="environment"/>
Line 37044 - <cd:command category="language" file="scrp-ini.mkvi" name="script" type="environment">