How do I get *8* data bits *no* parity?

[Steve Rudek]

We're running Micrport System V/AT release 2.4 and need to change the tty
default for incoming modem calls from the default (7 data bits even parity)
to 8 data bits no parity to better accomodate new callers.  About 6
months ago, under 2.2, I spent quite a bit of time experimenting with the 
gettydefs file.  As I recall, I tried changing the standard entry:

1200# B1200 HUPCL PARENB CS7 CLOCAL OPOST ONLCR # B1200 HUPCL SANE IXANY TAB3 #login: #1200

to:

1200# B1200 HUPCL CS8 CLOCAL OPOST ONLCR # B1200 HUPCL SANE IXANY TAB3 #login: #1200

but it didn't make any significant difference.  Why not?

Why does UNIX default to 7 data bits/even parity, anyway?  UUCP appears to
configure the line before calling out (once again, I'm drawing on
some fuzzy memories of experiments I ran long ago).  While I understand the
(intended) value of parity when doing file transfers, for interactive use
it seems generally ignored.  If I succeed in switching to 8 data bits will
there be any unwanted side effects I should beware of? 

I was told by one of the tech support folks at microport that the "#" in the
center of the gettydefs record delimits line condition BEFORE login from
line condition AFTER login.  Is this correct?  In general, I'd be fascinated
to hear the full story of what is really going on in a gettydefs entry.
While I can look up the supposed definition of some of these field mnemonics
(e.g., "PARENB" or "CS7") I feel that the UNIX documentation is extremely
inadequate in describing the available options and interactions in line
control settings.