Or copy this URL:
https://www.metalroofing.com/spirit/comment/8890/find/
I am not at all aware of this as a "metal" roof term.
"Butterfly" may be used though to refer to a roof geometry design where two eaves meet need the middle of a roof, for the purpose of channeling and collecting rain water.
11/7/2006
Isaiah Industries, Inc.
11/8/2006