double check symbol

[dvanderfaeillie]

Is it possible to append the double check symbol?
When typing \mainline{1. Nh4++} it only prints "1. Nh4+"

The "++"-double check symbol seems supported by Fide.

[lehoff]

Sorry for not noticing this earlier.
The PGN standard prescribes using # for mate, so that is what skak uses to parse the games. FIDE seems to be using the same, but there might be games using ++ from before PGN won the notation war.
Most programs stick to # for mate - I would prefer to support only the standard of PGN due to this.