an internal, constant, OID and a dynamically-created one. The latter cannot be constant because it needs to be freed after use.</p>

<p>These functions were not thread safe in OpenSSL 3.0 and before.</p>

<h1 id="RETURN-VALUES">RETURN VALUES</h1>

<p>OBJ_nid2obj() returns an <b>ASN1_OBJECT</b> structure or <b>NULL</b> is an error occurred.</p>

<p>OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or <b>NULL</b> on error.</p>

<p>OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return a NID or 