A function or statement which either get or sets the total length of the file whose file handle is its argument or the total amount of unused RAM.
In its normal usage, EXT# can be used to get or set the length of a file.
The file must have been opened before EXT# can be used to get or set its length.
When a file is resized the file pointer is moved to the end of the file if it would have otherwise pointed past the end of the file.
You can retrieve the amount of unused RAM in bytes by passing -1 to the EXT# function. Unused RAM is RAM outside BBC BASIC's memory map that is not currently being used by the TI-OS.