May be formatted inline or as a displayed block, depending on context.

Common attributes and common linking attributes.

any attribute

Any attribute in any other explicit namespace

choice

Indicates optionality.

Enumerated values:
“opt”	Formatted to indicate that it is optional.
“plain”	Formatted without indication.
“req”	Formatted to indicate that it is required.

rep

Indicates whether or not repetition is possible.

Enumerated values:
“norepeat”	Can not be repeated.
“repeat”	Can be repeated.

These elements contain arg: arg, cmdsynopsis, group (db.group), synopfragment.

The following elements occur in arg: text, abbrev, acronym, alt, anchor, annotation, arg, biblioref, coref, date, emphasis (db._emphasis), firstterm (db._firstterm), footnote, footnoteref, foreignphrase (db._foreignphrase), glossterm (db._glossterm), group (db.group), indexterm (db.indexterm.endofrange), indexterm (db.indexterm.singular), indexterm (db.indexterm.startofrange), inlinemediaobject, link, olink, option, phrase (db._phrase), quote (db._quote), remark, replaceable, sbr, subscript, superscript, synopfragmentref, trademark, wordasword, xref.