Word -@ is documented but not implemented (on PIC24)

[David C. Norris]

For consistency with @+ this might better be named @- anyway.

[Mikael Nordman]

I implemented it on pic18 only where I happened to need it.
The name -@ is fine because it predecrements.
@+ postincrements.

[David C. Norris]

Current documentation in wordsAll.txt:

-@         ( a-addr -- a-addr-2 n )
           Fetch from a-addr and decrement a-addr by 2

Would suggest the following instead:

-@         ( a-addr -- a-addr-2 n )
           Predecrement a-addr by 2, then fetch
           PIC18