3428     return wcs.err->status;
 
 3431 In 
this example, 
if an error was generated in one of the 
prjset() functions,
 
 3432 wcsperr() would print an error traceback starting with 
wcsset(), then
 
 3433 celset(), and finally the particular projection-setting function that
 
 3434 generated the error.  For each of them it would print the status return value,
 
 3435 function name, source file, line number, and an error message which may be
 
 3436 more specific and informative than the general error messages reported in the
 
 3437 first example.  For example, in response to a deliberately generated error,
 
 3438 the @c twcs test program, which tests 
wcserr among other things, produces a
 
 3439 traceback similar to this:
 
 3441 ERROR 5 in 
wcsset() at line 1564 of file wcs.c:
 
 3442   Invalid parameter value.
 
 3443 ERROR 2 in 
celset() at line 196 of file cel.c:
 
 3444   Invalid projection parameters.
 
 3445 ERROR 2 in 
bonset() at line 5727 of file prj.c:
 
 3446   Invalid parameters for Bonne's projection.
 
 3449 Each of the @ref structs "structs" in @ref overview "WCSLIB" includes a
 
 3450 pointer, called @a err, to a 
wcserr struct.  When an error occurs, a struct is
 
 3451 allocated and error information stored in it.  The 
wcserr pointers and the
 
 3452 @ref memory "memory" allocated for them are managed by the routines that
 
 3456 example above.  If enabled, when an error occurs it is the user's
 
 3457 responsibility to free the memory allocated for the error message using
 
 3459 out of scope will result in memory leaks (if execution continues beyond the