What do the numbers in the ISO 4217 currency codes mean? The International Organization for Standards (ISO) has a ISO 4217, which delineates currency codes, country codes, etc. for, well, international currency.

Alongside this, each country is given a three-digit numerical code number.  I've been trying to figure out what kind of designation process this has, but it appears to be random.  Why is it oddly (mostly) random?

They appear to somewhat progress alphabetically with new ones added to sometimes newer countries that appeared after the 1973 designations, but not always.  And there are way too many gaps for those countries that may have fallen off the map since then, so to speak.  What is the meaning of the numerical designation for ISO 427 labels on currency?  I find it hard to imagine it is just sloppiness.
From the ISO homepage this answer can be found:

The three-digit numeric code is useful when currency codes need to be understood in countries that do not use Latin scripts and for computerised systems. Where possible the 3 digit numeric code is the same as the numeric country code.
For currencies having minor units, ISO 4217:2015 also shows the relationship between the minor unit and the currency itself (i.e. whether it divides into 100 or 1000).
ISO 4217:2015 also describes historical codes in List three as well as the codes representing certain funds in List two.