Template:!/doc
| This is a documentation subpage for Template:!. It contains usage information, categories and other content that is not part of the original template page.  | 
Usage
This is the Template:Tn meta-template.
This is an auxiliary template allowing the encoding of "|" within template parameters. It is necessary if the character is used in wiki table syntax, or if the parameter is automatically wikilinked and you wish to use a pipe to specify different link text from the target page name. In other cases it is better to use "|". 
This template cannot be used for putting the character as text in a wiki table; in that case, again,  "|" can be used.
Note that no special template is needed for "!" (exclamation mark).
This is a high risk template, and it usually cannot be substituted (see conditions for substing on the section below).
Substitution
The template page states that {{!}} cannot be substituted. That's not completely true because it is perfectly okay to substitute {{!}} as soon as an unescaped "|" works as expected, i.e. after substituting the template containing {{!}}, or after eliminating an #if: containing {{!}}.
See also
- {{!!}}
 - {{!-}}
 - {{-!}}
 - {{broken bar}}
 - Template:Tn and related
 - Wikipedia:Qif conditionals
 - {{pipe}} - Note that this one looks like Template:Tlf but has a very different meaning for the MediaWiki parser and thus has different functionality.
 - Template:Tn
 - {{!(}}