Fide Default Mode Limitations

The two systems that SwissSys supports — the USCF and FIDE — have differences which require the program to behave differently in some situations depending on which system is active.

Most of them arise out of the stricter rules that FIDE places on its endorsed pairing programs.

Default Mode Setting

FIDE requires that a pairing program be set to run in FIDE mode by a standard invocation of the program. When you first run the program you are asked which mode you want to be the default. (If you have the FIDE-only registration of SwissSys, this and all other FIDE settings are forced.) Otherwise, FIDE arbiters should select FIDE mode when prompted.

If you need to change this, you can do so from the Rules for Pairing dialog.

FIDE Mode Limitations

With FIDE mode set as the default, or when the “FIDE rules” checkbox is enabled in the Rules for Pairing dialog, there are certain limitations and differences imposed.

Below is a summary of the main ones you will find in FIDE mode:

Only FIDE-approved pairing options are available in the rules for pairing dialog. Others will be grayed-out or invisible.
Only the bbpPairings engine is approved for use with SwissSys. Changing to a different engine is permitted, but only for unofficial tournaments. This includes the previously-endorsed SwissSys internal engine. Because this engine still uses the older pairing rules, it is no longer endorsed.
Some edit options are restricted. In particular, FIDE mode does not allow you to change pairings once another round has been paired. Should you need to do this, restore the round where the incorrect pairing happened, correct it, and proceed to re-do the pairings from there. (Alternatively, you could turn off FIDE default mode and FIDE rules temporarily, then edit the changes which SwissSys permits in the less restrictive USCF mode.) Similarly, you are not allowed to enter incompatible pairings and results when editing, even if only temporarily.
The pairing-allocated bye (PAB) will be marked in the pair chart for FIDE pairings, but not for USCF pairings, since that is not an element of USCF pairing rules.
In the pair chart, the “Repair” option is not available.
A few pairing options that are not endorsed by FIDE are nonetheless available for casual, unrated tournaments if you opt for the SwissSys engine (running the older FIDE pairing rules) or if you use USCF pairing rules instead.