I'm pretty sure it hasn't changed. The reason it is maybe not giving the results we expect is because the search behavior. If the record has more than one 999 field, then it will still be included in the results for
NOT 999a:vvc*
because the other 999 fields match. For example, this search returns results
NOT 999a:vvc AND 999__a:vvc
because there are records that have both a 999 = vvc and a 999 != vvc
Not sure if the title makes sense, but basically I want this query to work again:
https://metadata.un.org/editor/records/bibs/search?q=999__a%3A%2F%5E%5Ba-z%5D%7B2%7Dq202408%2F+AND+NOT+999__c%3A%27r%27+AND+NOT+999__a%3Avvc*+AND+NOT+091%3ARES&start=1&limit=250&sort=updated&direction=desc&search=999__a%3A%2F%5E%5Ba-z%5D%7B2%7Dq202408%2F+AND+NOT+999__c%3A%27r%27+AND+NOT+999__a%3Avvc20240813+AND+NOT+091%3ARES&engine=community&format=brief
Copying Joe's comment from the chat:
I'm pretty sure it hasn't changed. The reason it is maybe not giving the results we expect is because the search behavior. If the record has more than one 999 field, then it will still be included in the results for NOT 999a:vvc* because the other 999 fields match. For example, this search returns results NOT 999a:vvc AND 999__a:vvc because there are records that have both a 999 = vvc and a 999 != vvc