i>def_purpose</i> and <i>purpose</i> arguments can have the same purpose values as described for X509_STORE_CTX_set_purpose() above. The <i>trust</i> argument can have the same trust values as described in X509_STORE_CTX_set_trust() above. Any of the <i>def_purpose</i>, <i>purpose</i> or <i>trust</i> values may also have the value 0 to indicate that the supplied parameter should be ignored. After calling this function the purpose to be used for verification is set from the <i>purpose</i> argument unless the