Waterloo Structured BASIC
Waterloo Structured BASIC (product number VIC-1001) was a utility cartridge for the VIC-20 providing an extended form of the BASIC programming language. The cartridge was manufactured & sold by Commodore Business Machines in Canada (and possibly only in Canada). Confusingly, CBM Canada chose the product number VIC-1001, which was a number already in use for the VIC-20 as sold in Japan.
The cartridge was actually called "Waterloo Structured BASIC". This is the proper name of the language, the name shown on the cartridge box and the printed on the manual. However, the cartridge label was mis-printed as "Waterloo Structural BASIC".
Waterloo Structured BASIC was developed as a programming language by the University of Waterloo in Ontario, Canada. The Computer Science department of this University had previously developed the SuperPET computer with Commodore in Canada. The SuperPET contained used the programming language Waterloo Structured BASIC (among others).
These cartridges seem to have been produced in low quantity (burned onto EPROMS and packed in generic brown utility cartridge boxes with stick labels). The cartridge was not known or even suspected to exist by the majority of VIC-20 users and collectors until 2006, when the ROM image was finally archived by a DENIAL forum member.