Perhaps it's simpler still --
"x" OP_3 OP_MOD
OP_IF "foo"
OP_5 OP_MOD
OP_IF "bar" OP_CAT
OP_ENDIF
OP_ELSE
OP_5 OP_MOD
OP_IF "bar"
OP_ENDIF
OP_ENDIF
Perhaps it's simpler still --
"x" OP_3 OP_MOD
OP_IF "foo"
OP_5 OP_MOD
OP_IF "bar" OP_CAT
OP_ENDIF
OP_ELSE
OP_5 OP_MOD
OP_IF "bar"
OP_ENDIF
OP_ENDIF