I don't know whether this is a bug in documentation or code, in documentation for symbol indexes Diffusion User Guide: Symbol Indexes there is an example at the end of document.

$ ./scripts/symbols/import_repository_symbols.php rREPO < symbols_data

if I include the r before callsign like this example, I will get the following error:

Repository 'rTXE' does not exist

but without the r it works fine