Using ALT-X for "long" (non BMP) Unicode characters

Question

This week I discovered that Alt-X does work for Unicode characters where the code is longer than 4 hex digits. The trick to make it work is to type 8 digits if you need more than four.

For instance, if I want U+1133C (Grantha Sign Nukta) in my text, I can type 0001133C, then press ALT-X and I’ll get the character. If I left out the initial zeros, ALT-X would leave the first 1 and give me U+133c.

Similarly in the character inventory, Paratext lists the code for these characters as 8 digits.

A different trick is needed to add characters like this in autocorrect.txt:

Handling "long" (non-BMP) Unicode characters in autocorrect.txt Helps

Some Unicode characters have a code longer than 4 hex digits. For instance David Rowe was trying to help someone who needed to type U+1133c GRANTHA SIGN NUKTA. The usual method of \u followed by the digits fails with any code longer than 4 digits. (A Unicode character outside the Basic Multilingual Pane). But it is possible to write this as a string of two 4 digit Unicode characters if converted to UTF-16. So this rule would give the desired character when typing two periods: ..-->\ud804\udf…