Start of match \zs seems to break my pattern

Question

I am playing around with vim syntax, matching expressions like name.subname regardless of their layout. Here is a match pattern I came upon which does exactly what I want:

Now, I wish that subname would be the only colored part of my matches. This is a job for \zs, right? Here is the result:

Why is this so? Why does \zs break my pattern? How can I get all subnames in the first section colored and not the ones in the second section?

Answer 1

Well, here is my explanation: there are restrictions on multi-line patterns for syntax highlighting: \zs cannot be used if it makes it jump to a line which is not where the pattern started:

:helph syn-multi-line

And here is a neat workaround with the keyword contains

highlight link SubGroup Error
syntax match SubGroup '\<subname\>' contained
syntax match Constant '\<name\>[ \n]*\.[ \n]*\<subname\>' contains=SubGroup

Also, here is another, maybe more efficient one: only highlight the end of the pattern:

syntax match Error "\<name\>[ \n]*\.[ \n]*\<subname\>"he=-6

it seems to randomly color or not the intermediate . though.