[Math] How to apply stylistic variants to oper operator?

I am writing an article with set-theoretic formulas.

I found this question which hinted me to the use of the oper operator instead of my ugly workaround for the lack of an “union” or “inter” operator. The basic formula is:

oper %Ux222A from {<?>} to {<?>} expression

where Ux222A is the Unicode code point for the union symbol (I was lazy to define a new symbol such as %union).

This works fine, but I’d like to have the symbol in bold and somehow bigger. I tried

oper { bold %Ux222A} from {<?>} to {<?>} expression

but it does not work. The brace becomes the operator and the formula interpretor displays error indicators (inverted question marks) with subsequent items.

Does anyone know how to apply style variants (bold, size or even color) to oper operator?

Update:

Question closed because plain use of oper gives the expected result.

Playing around a bit led to this example: ask60841UglyUnion001.odt. (%Ux222A must be defined under ‘Tools’ > ‘Catalogue’.)

But: There are standards. Why not regard them?

(Editing:)

I posted an answer here despite the fact that I do not need ‘Math’ much since I am retired. I simply am still interested. I would like a well working formula editor as part of free office suites, and I remember the problems coming up when I started to migrate many formulae more than 15 yeras ago from (reduced) MathType in Word to StarOffice. Bugs I experienced that time are still present. See How to get better scalable bracket? where I even offer sponsoring. There was not a single comment on that. I feel Math to be a kind of orphan in the community. (I did not go https://freedomsponsors.org/issue/add, however.)

Back to the subject: As the new example (See attached; from H. Schubert, Topologie) should demonstrate, the automatism treating a unary operand differently is working rather well. I do not feel any need to change the style.

ask60856RangeableOperators002.odf

As you write, this is ugly: attributes for the operator are set beforehand, which forces to reset the attributes for every other component of oper.

Which are the standards? Math ones or LO/ODF one? I always prefer to apply standards but I don’t know all of them. Please give references.

Sorry! I was unclear. I do not know specifications for how ‘Math’ should do it. In specific I could not find anything about it in OASIS ODF papers. And the guide tells us “how to” in many cases but does not refer to specifications.There also are severe bugs in ‘Math’ unresolved for years now.

The standards I talked of are understood on the level of “good practise” as regarded by professional typesetting - and possibly specifically by the working of TEX.

@Lupp Of course, TeX is THE reference for formula typesetting, but I find it is a lot of work to learn it for an occasional use (I am in the same situation and mood as you). I was not aware that Math was left so much apart from LO development effort. Due to the inconvenience with oper, I think i’ll use a workaround with vertical stacking.

Remark: in your sample, you use %UxE139 which is in a private use area of Unicode. Is there any particular reason why you don’t use %Ux229 or %x22C2

@ajlittoz "… you use %UxE139 which is in a private use area of Unicode. Is there any particular reason why you don’t use %Ux2229 … "

Not exactly. The thing was offered via ‘Tools’ > ‘Catalogue’ > ‘Edit’ and it worked out to be bigger…

By the way: Do you know TexMaths Homepage? If so, what were youre experiences?

@Lupp Discovered the link, seems interesting but needs to know LaTex.

I’ve gone on with my Math fiddlings. After simplifying my equations, it seems oper and its default formatting fits my needs. I only slightly adjusted the subscript size ratio so that it remains readable (I have a subscripted subscripted object, like P_{N_i} and the i must not be too small.