Q. They didnít use to allow such goings-on here.
A. didnít use◊ used not√. Inelegant form of verb used, though the expression (didnít use) is frequently used by inelegant speakers.

Inelegant speakers must make up over 90% of the population, then. Ďused notí sounds odd these days to most people.
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I havenít understood what has been mentioned in the above text thus far because I am not familiar with the word "
inelegant" although I have checked the dictionary. As a result, according to the above explanation, what is the difference between the following pairs, please?

I didnít use to smoke.

I used not to smoke.