-int uper_open_type_put(asn_TYPE_descriptor_t *td, asn_per_constraints_t *constraints, void *sptr, asn_per_outp_t *po);
+/*
+ * X.691 (2015/08), #11.2
+ * Returns -1 if error is encountered. 0 if all OK.
+ */
+int uper_open_type_put(const asn_TYPE_descriptor_t *td,
+ const asn_per_constraints_t *constraints,
+ const void *sptr, asn_per_outp_t *po);