is mentioned by

Thm* x:Label, ls:Label List. x ls (x ls)	[assert_lbls_member]
Thm* l1,l2:Label. l1 = l2 l1 = l2	[eq_lbl_iff]
Thm* l1,l2:Label. l1 = l2 l1 = l2	[assert_eq_label]
Def Label == {p:Pattern| ground_ptn(p) }	[lbl]

In prior sections: bool 1 list 1 mb basic mb nat union mb list 1 rel 1

Try larger context: GenAutomata