Try to check the Custom.xtm (open in Notepad) file in the SE directory.
I cannot remember if all in, but worth to check.
At this moment I have not accessed to SE on my computer.
I assume, that this drop down list shows the existing hole table files (Excel files) in Your Holes Directory in alphabetic order.
So "ANSI" beginning with an "A" always will be the first, as long as their exists another file with a character before the "a".
I just have created a new file (copy) from ISO and have called it "01_ISO" - and - Yes it is appearing in the leading position instantly after.
@hawcadthanks for information. Seems that your answer is solution. I thought that maybe it's possible to set order differently since my default value of "Standard" is set to "ANSI metric" (it's second hole table file when sorting alphabetically).
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Yes, "ANSI Metric" is the second in the list, but it is shown as first when changing the hole.
Since the existing hole - in that case - has a e.g. 8.0mm diameter, which doesn't exist in the Inch tables.
Therefore the first entry in the list is the table which has the existing diamter in it.
If You try to change an Inch hole You will see the "ANSI Inch" table as first entry in the list.
FYI there is an existing master ER requesting the functionality to specify or default the holes database file used – master ER# 1127880