The Spreadsheet Buffer is an important part of the OSLO data structure. So far as OSLO is concerned, the spreadsheet buffer is an output-only data structure, but it serves as the principal source of communication between the program and user macro commands (called star commands, see below). A spreadsheet buffer is attached to each text window. Whenever OSLO writes floating-point numeric output to the window, a copy of the output, having full internal precision, is placed in the spreadsheet buffer. The various buffer elements can be addressed by the SCP and CCL macro languages, used in data entry, or displayed in the message area by clicking on the number in the text window.