Problem

You want to modify the output of a tag.

Solution

Use a global filter on the tag.

Discussion

Global filters are special attributes that can be applied to any tag to transform its output before publishing. For instance if you wanted to display entry titles in all capital letters you could apply the upper_case global filter like so:

 <$MTEntryTitle upper_case="1"$>

Multiple filters may be used and follow an internal system-designated order for processing, not the order in which they appear.

For a list and description of all built-in global filters see Appendix B and Appendix A.