Are the flags documented? can this function be used to specify same as virsh undefine --nvram "name of VM"

libvirt_domain_undefine_flags($res, $flags)

[Since version (null)]

Function is used to undefine(with flags) the domain identified by it's resource.

`@res [resource]`:	libvirt domain resource, e.g. from libvirt_domain_lookup_by_*()
`@flags [int]`:	optional flags
`Returns`:	: TRUE for success, FALSE on error