How may I select tags added by mine own in the focus engine? I want to filter albums by more then one tag a time.
There’s a tag button two buttons over from the focus button. Click that and select the tag(s) you want to focus on. These can be combined with selections from the focus panel as well.
Ok, thanks for the hint. I was searching something like this inside Focus panel. Externally chosen tags are considered in Focus, so that’s Ok though a bit strange 
I’ve played with ‘Focus on tags’ a bit and it seems like only logical sum is implemented. If You check two tags, the result contains everything, what matched first tag OR second one. The more tags You check, the more items are in the result.
How can I choose things matched first AND second tag, to narrow result accordingly? I mean logical product instead of sum.
The current logic is AND between Focus Tools and OR within a particular Focus Tool. So if I want Blues music between 1970 and 1975 Focus will show me albums which are Blues AND 1970-1975. Conversely if I Focus on both Blues and Classical, I will get Albums which are Blues OR Classical.
Remember also, that clicking on the + sign of a Focus toggles it to - in which case it will show all Albums except those satisfying the Focus.
User tags are treated as a Focus tool, so if you want to use AND find a Focus criteria which best suits your needs rather than adding a further User tag to the Focus.
There is a Feature Request to enable more user defined logic to Focus searches.
I’ve topped up this Feature Request, maybe it would be implemented as AND/OR switch, just like present +/- switch in focus tags.
By the way, am I right that Focus is inaccessible on iOS remote? We may access only focuses prepared on Mac and saved as a bookmark, yes?
Yes, the screen limits preclude implementation of some elements of Roon in the iPhone and Focus is one of those. The iPad app is full featured (except for Export).
I see, thanks for information