The collage system takes a grammar file as its only input. This file contains a description of the collage grammar and the derivation that should be applied to it.
In the first phase the system loads this file into memory and analyses its structure. This analysis consists of a syntax check, conversions and calculations. If the first phase succeeds then the system has built up an internal representation of the collage grammar and the derivation.
In the second phase the output of the grammar is generated which is independent of the specified derivation. In the third phase the collage grammar is derived and corresponding output is generated. The output of the system always comes in two flavours: A Postscript output and a screen output. Both kinds of output are organized in pages that correspond to the derivation.
If the system is used interactively then a viewing phase may follow in which the user can view the generated screen output.