optional — Optional information
optional ::=
(text | phrase
db._phrase | replaceable
| Graphic inlines | Indexing inlines | Linking inlines | Ubiquitous inlines)*
The optional
element indicates that a specified
argument, option, or other text is optional. The precise meaning of
“optional” varies according to the application or process
being documented.
Formatted inline.
Optional arguments in a synopsis
are usually
given special typographic treatment, and often they are surrounded by
square brackets. The optional
tag is expected to
generate the brackets.
Outside a synopsis
, the typographic treatment
of optional
is application specific.