c structure or NULL is returned.</p>

<p>X509V3_add1_i2d() adds extension <i>value</i> to STACK <i>*x</i> (allocating a new STACK if necessary) using OID <i>nid</i> and criticality <i>crit</i> according to <i>flags</i>.</p>

<p>X509V3_EXT_d2i() attempts to decode the ASN.1 data contained in extension <i>ext</i> and returns a pointer to an extension specific structure or NULL if the extension could not be decoded (invalid syntax or not supported).</p>

<p>X509V3_EXT_i2d() encodes the extension specific struc