Simply I found out that if I put
<item>play <ruleref special="GARBAGE"/></item>
<item>stop <ruleref special="GARBAGE"/></item>
<item>set <ruleref special="GARBAGE"/><ruleref uri="#numbers"/></item>
calling the id reference after set will take just "set 1", "set 2", but doesn't accept "start 1" because there isn't the reference after the name.