pcidevs has this line for IGS:

    vendor INTERGRAPHICS  0x10ea	Integraphics Systems

note that the identifier is spelled with 'r', but the string is
spelled without the 'r' - which seems confusing.

The Tvia FAQ says

    http://support.software911.com/tvia/searchdetails.asp?pno=1

"Tvia formerly known as IGS Technologies / Integraphics Systems Inc."
I.e. their own "official" spelling is without 'r'.

Is there any reason the identifier is spelled as INTERGRAPHICS with
'r'?  Some backward compatibility?

Google search shows a lot of documents that use one spelling or the
other (sometimes even within one document both names are encountered).

SY, Uwe
-- 
uwe@ptc.spbu.ru                         |       Zu Grunde kommen
http://www.ptc.spbu.ru/~uwe/            |       Ist zu Grunde gehen