( resource id)
Returns an errornumber for the target (last request) identified by
id. The error code is either a Z39.50 diagnostic
code (usually a Bib-1 diagnostic) or a client side error code which is
generated by PHP/YAZ itself, such as "Connect failed", "Init Rejected", etc.
yaz_errno() should be called after network
activity for each target - (after yaz_wait()
returns) to determine the success or failure of the last
operation (e.g. search). To get a text description of the
error, call yaz_error().