ASSET_A_160: Ada/X Toolkit Architecture This report provides a detailed description of the Ada/Xt toolkit architecture. The purpose of this report is to describe the Ada/Xt architecture in terms of system-independent package specifications, and to describe the analysis which contributed to major design decisions. The emphasis on system-independent package specifications rather than language independent specifications derives from recognition that the C language interfaces defined in the X Toolkit (Xt) Intrinsics definition are almost language independent -- for languages in the Algol tradition, including Ada. The Ada toolkit design verifies this claim, since there is a very close syntactic mapping of types and interfaces from the Ada specification to the C specification. This product was developed as part of the Software Technology for Adaptable, Reliable Systems (STARS) program, sponsored by the Advanced Research Projects Agency (ARPA).