Consider the following example:
count(x[,r])
The font used for
"count(,)"
indicates this is literal text.
In other words this is exactly what appears on the screen (which could be either
output or typed input).
Note that
"x"
and
"r"
are in italics (with slanted font),
which indicates these are formal argument names rather than literal text.
You replace such names with whatever is desired.
Optional arguments are indicated using two alternative conventions.
In the above example they are enclosed in brackets,
indicating that
",r"
is optional.
This convention is common in computing documentation.
Use has also been made of the the alternative (commonly used in Tcl documentation)
of surrounding the optional component with question marks.
For example:
count(x ?,r?)
Alternatives are indicated with a vertical bar
"|", as in the following:
nap_info bytes|sequence
which indicates that the argument can be either
"bytes"
or
"sequence".