I've been trying to understand how the "mask" feature works in scid and how to use it for training opening lines. So far I did the following:

  1. open a database of master games in scid
  2. open the tree window
  3. while playing through an opening line, right click with the mouse on a move in the "tree window" and select add to mask for all moves that interest me
  4. in the same "tree window" right click on a move and select a marker such as "main line"/"dubious"/"Include". This step I only did very rarely.
  5. save the mask by left clicking "tree window"->"mask"->"save".

I did this whole procedure separately for my white and black repertoire, so I get two masks: "whitemask"/"blackmask".

Am I on the right track with this procedure? What else could/should I do with the mask?

How do I use the mask? I noticed that sometimes in the chessboard window, it shows me the possible alternative moves from the mask by arrows. However I did not figure out when it does this, or how to enable this feature (which I find quite useful). I'd like to play through an opening making moves for both sides, while having the arrows show me the possible moves according to my mask. How can I do this?