what is check_trust() do in X509_verify_cert()?

[Wu Junwei]

Hi,all       I have a question on certificate verifying. In X509_verify_cert(), after checking the prupose (my understanding is to check the extension of the V3 certificate), it checks the so-called trust :    if (ctx->trust > 0) ok = check_trust(ctx);   I do not understand what is this used for? Why only does the check_trust() when ctx->trust > 0 ?     Thanks in advance. wjw