UniversalElementFactory provides supports to define a macro to reuse
the definition. Take the following Macro Definition for example:
<macroDef id="myMacroDef">
<string value="_value"/>
</macroDef>
To reuse this definition, you can
define a macro instance:
<macro id="myMacroInst" macroDef="myMacroDef" _value="Value"/>
This
definition equals to <string value="Value"/>