In HP-UX 10.00-10.20, a special module exists which provides XTI access
over the BSD stack - TLI is not supported. TLI, for the most part after
SVID 3 volume 5, has stopped evolving and is being replaced by XTI in
most implementations.  XTI is standardized by X/Open and the current
versions from most vendors should be XPG4 compliant with some being
branded as the branding test suites are made available by X/Open.

Note the reason one needs a streams-based TCP is that both TLI and XTI
rely upon a streams-based module, timod, to provide specific functionality
within the kernel and this module needs to be pushed upon the transport
stack.  Since HP-UX uses a BSD transport which is not streams-based and
is therefore incapable of having a streams-based module pushed upon it,
one can not run TLI/XTI directly upon it, and, hence, a special streams
module was created to provide this functionality for HP-UX 10.0.

As of HP-UX 10.30, the BSD-based transport is replced by a Streams-based
one.  XTI no longer requires a special streams module.  In the past, where
one would open /dev/inet_cots to get TCP, one can open /dev/tcp and get
TCP.