Notes on lists, tight and loose, and @compact attribute

[Mark Giffin <mark@markgiffin.com>]

Executive Summary

1. We discussed adding tight/loose lists to MDITA to match CommonMark spec.
2. Related to this, we talked about adding @compact attribute (from DITA 1.3) to XDITA and HDITA.
3. However, @compact was removed from HTML5 (replaced with CSS as it should be).
4. This question arose: Should @compact be removed from DITA 2.0? Isn't it an archaic styling attribute?

    Still to be decided:

• How to handle tight/loose lists in MDITA
• How will that affect XDITA and HDITA, if at all
  

Background Info

    This subcommittee discussion came up because of the following DITA
    OT bug, which applies only to MDITA and Markdown, not XML DITA:
    
    https://github.com/jelovirt/org.lwdita/issues/175

Summary of Bug 175

    In the original Markdown, to make HTML output list spacing tight,
    you would put carriage return between list items. To give the HTML
    output looser spacing, you'd put a carriage return between list
    items. This idea was carried over into the CommonMark Markdown
    standard, which MDITA is based on. Here is the CommonMark spec on
    this subject:
    
    https://spec.commonmark.org/0.30/#loose
    
    Even though MDITA is based on CommonMark, MDITA was not designed to
    support tight and loose lists like this, so it violates CommonMark
    on this point. This pretty much applies only to HTML output. For
    other output like PDF, it probably does not really apply. Or should
    not apply. This caused us to look at the @compact attribute for DITA
    1.3 XML.

The @compact Attribute Was Removed in HTML5

    In HTML5, the @compact attribute has been removed. It was deprecated
    in HTML 4, 20 years ago. Modern popular browsers do not support
    @compact, they ignore it. It can be replaced with CSS.
    
    Mozilla Developer Network docs on @compact in <ul>:
    
    https://developer.mozilla.org/en-US/docs/Web/HTML/Element/ul
>  compact - Deprecated Non-standard
>       Warning: Do not use this attribute, as it has been deprecated: use
>       CSS instead. To give a similar effect as the compact attribute,
>       the CSS property line-height can be used with a value of 80%.
>

DITA 1.3 Still Supports @compact

    DITA 1.3 @compact attribute in the spec:
    
    https://www.oxygenxml.com/dita/1.3/specs/langRef/attributes/commonAttributes.html#common-atts__compact
> Indicates close vertical spacing between list items.
>       Expanded spacing is the processing default. The output result of
>       compact spacing depends on the processor or browser. Allowable
>       values are:
>       yes - Indicates compact spacing. 
>       no - Indicates expanded spacing.
>

DITA Open Toolkit Support for @compact

    DITA 1.3 XML content using @compact:
    
    Running XHTML output through the latest DITA OT version (4.1.1) with
    DITA 1.3 XML content using @compact on <ul>, produces results
    in XHTML like this:
    <ul class="ul" compact="compact">
ÂÂÂÂÂÂÂ <li class="li">one</li>
    But since @compact is archaic HTML syntax, it is unsupported by
    modern browsers. You could probably make a CSS class that operated
    on @compact, but why bother. Use HTML @class.

• XDITA does not support @compact
• HDITA - Does not support @compact. And since @compact is gone in HTML5, use CSS instead.
• MDITA - DITA OT does not recognize tight/loose lists in MDITA.
  

    That's it.
    
    Mark Giffin