sax :: InputSource :: system_id=
# The system identifier as a string.
#
# If its an URL, it must be fully resolved (it may not be a relative URL).
#
# Applications may set `public_id` to include a
# public identifier as well, or set `encoding` to specify
# the character encoding, if known.
var system_id: nullable String = null is writable
lib/sax/input_source.nit:72,2--79,50