From DSL Wiki
Application type: Spreadsheet
Scheme In A Grid(Siag) is the spreadsheet part of the Siag Office suite, which also contains Egon Animator and Pathetic Writer(PW). Siag Office uses the Offix DND Drag-and-Drop protocol. Siag is a spreadsheet based on X and Scheme. Being based on Scheme allows any user to expand the functionality of Siag in just about any way imaginable. It can read and write IBM Lotus 1-2-3 files for inter-operation with other well-known spreadsheet programs. You can enter expressions in several languages: C, guile, SIOD, Tcl.