Apple Lisa Pascal Text File Format

Pascal text files on Apple Lisa are a sequence of 1024-byte pages. The first page is a header present at the beginning of the file. It's not considered part of the actual contents of the text file, but is used by the editor to store formatting information, etc.

Each text page following contains some number of complete lines of text and is filled with null characters after the last line.

The end of a text page must terminate with at least one null. For simplicity, the first instance of a CR-null sequence will signal the end of the page.

A line is a sequence of zero or more characters followed by a CR. A line may be arbitrarily long.

A sequence of spaces at the beginning of a line may be compressed into a two-byte code, namely a DLE character (ASCII 16) followed by a byte containing 32 plus the number of spaces represented.

A null text file consists of only the 1024-byte header page.