I would like to add to the list of indexes to be able to selectively choose ("is in", "is not in").

See the following:
1.) Physical item: Material Type.
2.) Title: Bibliographic Format.
3.) Title: Material Type.
4.) Title: Medium Type.
5.) Title: Resource Type.
6.) Physical item: Call Number Type.
7.) Physical item: Item Call Number Type.
8.) Physical item: Process Type.
9.) Physical item: Provenance Code.
10.) Physical item; Temporary Call Number Type.

The driving force behind this is to create logical Alma Sets for OAI-PMH Sets for Resource Sharing so that we don't have to create itemized sets for these and manually have to update the Alma Set to include updated information. We have some material types we'd like to not share and simply defining them via location isn't working well for us.

Many thanks in advance if you will add the possibility to choose "not equal" or the operator "NOT" for other search indexes.
I'm not sure if I understand the meaning of "child records". For us it would be very important to be able to exclude certain keywords occurring in the same record. For example, we would like to find out all records with the words "gnd-satz-s ubs", but not "Neuansetzung" in field 901 (Search in "All titles", NZ; see picture attached). Another example: we would like to find out all records with the sentence "SLSP noch nicht geprüft" in field 667, but not "CH-BaUGNS" in field 040 (Search in "Authorities", CZ).
Will this be possible in the near future?

As far as I can tell and as far as our needs are concerned use case 1 will do. I am not sure about use cases 2a and 2b. Use case 1 would correspond to the operator IS NOT we used to have in most if not all library catalogs and databases I came across in the last 25 years, am I right? That would be very handy. Even if you don't use IS NOT every day - in those cases you need it, it's hard if not impossible to figure out an alternative query. And I just don't see why Alma shouldn't be able to do what all kinds of old-fashioned library catalogs were able to do ...

Ex Libris is working on adding the "is not" operator whenever is possible. There are two different major use cases:
1. Condition in the same level as the entity being requested. For example All items not in a specific library.
2. Condition in a lower level (child) than the entity being requested. For example titles without items in Library A.

The first use case can be addressed and if there are gaps we will close them. The second use case is the problematic one. There are two sub-use cases for the second case Condition in a lower level:
2a. Entity partially meets the condition. For example, titles that part of their items are not in library A.
2b. Entity fully meets the condition. For example, titles that *all* of their items are not in library A.

The 2b sub-use cases require a totally different search infra and are not trivial.
The question is if sub-use case 2a is relevant or not. If 2a is not relevant then we can block the option to use "is not" operator for the level below. If it is relevant then the user should be aware that it will provide an answer to sub-use case 2a.

We have just changed from Aleph to Alma and are also very much missing the "IS NOT" operator, e.g. in the search indexes of the CZ "Authorities". Especially for cleaning up-work in Authorities it is absolutely necessary to be able to exclude criteria. The Boolean Operator "NOT" is basics for librarian work and we just don't understand why it should be missing.
We would be very grateful if the operator "NOT" could be allowed just as "AND" and "OR".

When doing an "electronic titles" search there is no "IS NOT" operator for "electronic collection name". Please add the IS NOT operator here. Interestingly, when doing an advanced search of "electronic collections", you CAN say electronic collection name "IS NOT" X.