ksh88 changing single quotes to double quotes inside heredocs?

Here are my notes when I discovered this same bug several years ago.

Test script:

#!/bin/kshcat <<EOF  $PWD "$PWD" '$PWD'EOFecho `cat <<EOF  $PWD "$PWD" '$PWD'EOF`echo $(cat <<EOF  $PWD "$PWD" '$PWD'EOF)

Output for different shells:

(NOTE: works as expected)

 /home/jrw32982 "/home/jrw32982" '/home/jrw32982' /home/jrw32982 "/home/jrw32982" '/home/jrw32982' /home/jrw32982 "/home/jrw32982" '/home/jrw32982'

(NOTE: single quotes replaced with double quotes and variable not substituted)

 /home/jrw32982 "/home/jrw32982" '/home/jrw32982' /home/jrw32982 "/home/jrw32982" '/home/jrw32982' /home/jrw32982 "/home/jrw32982" "$PWD"

Work-around:

Compute the single-quoted string externally from the here-file
```
abc=xyzSTR="'$abc'"x=$( cat <<EOF  $abc "$abc" $STREOF)
```

Use the here-file in a function instead of directly

fn() {  cat <<EOF    $abc "$abc" '$abc'EOF}abc=xyzx=$(fn)

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