Can you name all special chess notation cases?

Sometimes it's mate, sometimes it's double check.

But I think ++ isn't officially used for either.

But neither was my e.p.

So I guess you could get to 10 with

gxf7e.p.++

Yeah he got 7 chars with equals sign. I’ll check the FIDE website to see if they use it or not. And ++, e.p., and the others

At any rate, you could always append a !! to the end

And if you did it in binary, it could be really long, like 100100100010100001010 for a move

The website says that ++ and e.p. (and x) are allowed, but optional. Use of the = sign to denote promotion is NOT permitted, in fact it is used to denote a draw offer

LOL, I was think'in tha' same thingy...  always reduce to binary then ya' can convert to any count'in system... Hex, oct  base 10,back to binary, 2's complement for subtraction via addition.. etc, etc. 

When one throws out a long binary string like yours, I automatically convert to them all, but thats what chess and insanity does to one. 

Thats true. There is a tactic on site which allows you to checkmate by long castling.

JVM will do the binary for me. Im still not a god. I cant convert binary or hex to decimal by just seeing them. 

I just had a really cool idea but it might not be allowed... what if you promoted your e pawn to a rook and castled with it (assuming neither your king nor your new rook have moved, there are no pieces in between and your king is never in check)? And if you gave checkmate on the same move, it would be O-O-O-O-O-O++ (13 characters)!

Notation used for this topic is chess.com´s notation. Chess.com uses "=" when promoting. I am not sure if it uses "++" for double check. I think it does not. 

Chess.com uses just one "+" for double check. Sad.

Seems like longest notation possible is 7 characters long. 

Nf6xe8Q#

8

(2,7)x(1,8)=Q#

14 characters

A knight taking on e8 and becoming a queen?

Strange variant.