${$} throwing syntax error when use in cat << EOF on ksh93 93u+ .

[Saikiran-m]

Solaris 11 that ship with ksh93, the following behavior is observed:

Version of ksh93 on system:
~# ksh --version
version sh (AT&T Research) 93u+ 2012-08-01

The issue:
echo ${$} working fine but echo ${$} throwing syntax error when use in cat << EOF.

Recreation steps followed below:
Case 1: with $$
:# echo $$
1323
:# cat << EOF

$$
EOF
1323

Case 2 : with ${$}
:# echo ${$}
1323
:# cat << EOF

echo ${$}
EOF
/usr/bin/ksh: syntax error: `$' unexpected

[McDutchie]

For anyone else reading: This is fixed on the ksh 93u+m fork.