[Jprogramming] Questions about a.

[David Vaughan]

Why is it that:

   a.

and

   8 32$a.

make J hang?

but:

   1 2 3{8 32$a.
 !"#$%&'()*+,-./0123456789:;<=>?
@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_
`abcdefghijklmnopqrstuvwxyz{|}~

works?