V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

TLI
       Transport Layer Interface


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

TLI
       Transport Level Interface (AT&T)


The Free On-line Dictionary of Computing (30 December 2018):

Transport Layer Interface
TLI
Transport Level Interface

    (TLI, or "Transport Level
   Interface") A protocol-independent interface for accessing
   network facilities, modelled after the ISO transport layer
   (level 4), that first appeared in Unix SVR3.

   TLI is defined by SVID as transport mechanism for networking
   interfaces, in preference to sockets, which are biased
   toward IP and friends.  A disavantage is that a process
   cannot use read/write directly, but has to use backends using
   stdin and stdout to communicate with the network
   connection.  TLI is implemented in SVR4 using the STREAMS
   interface.  It adds no new system calls, just a library,
   libnsl_s.a.  The major functions are t_open, t_bind,
   t_connect, t_listen, t_accept, t_snd, t_rcv, read, write.

   According to the Solaris t_open man page, XTI (X/OPEN
   Transport Interface) evolved from TLI, and supports the TLI
   API for compatibility, with some variations on semantics.

   (1999-06-10)