Template:IA

General case
Identifier and text can be used without naming them. The  argument is optional.

This addresses regular linking.

Specific file in an item
The  argument is optional and implicit.

is an explicit argument, so you must address it with.

Link to a collection's about page
The  argument is optional and implicit.

is an explicit argument, so you must address it with. Set its value to true.

Technically,  can always be appended, but the parameter it adds to the URL is meaningless except when addressing a collection.

Show a thumbnail instead of link text
The  argument is optional and implicit. It will set the thumbnail's alt text.

and  are explicit arguments, so you must address them with   and.