Filter for field containing double backslash?

This is a weird one...

I would imagine using \ in any field might cause problems with any editing or playback software.

That being said, I have never done so, but I've encountered a bunch of albums in my collection that have multiple years separated by \\ in the year field/tag.
I think it's to denote the original release date vs. reissue, etc.
For instance, one album has 1990\\1988 in the year field for every track.

If I add Year to the columns, the only date shown in the Year column for this album is 1990.

If I change one track to 1990\1988, both column and tag panel show 1990\1988 and I can filter using: year HAS "".

How come \\ will show in the tag panel but not in the column?
Is there any way to filter for a double backslash?

Thanks!

It is rather unusual to have multi-values in the tag-field YEAR, but in the tag-field GENRE it is usual.
If you want to see the multi-values for the YEAR column in the list view, then adapt the settings for this column to ...
value=$meta_sep(YEAR,'\\')

Filter: NOT "$meta(YEAR,1)" IS ""
Filter: "$meta_sep(YEAR,'')" HAS ""
Filter: "$meta_sep(YEAR,'\\')" HAS "\\"
Filter: "$meta_sep(YEAR,' :smiley: ')" HAS " :smiley: "

Filter: YEAR MATCHES "\\"
Filter: YEAR HAS "\\"
Note: These both filter strings may not work, because a tag-field having a sequence of two backslashes won't exist in Mp3tag tagging environment.
Note: The operator MATCHES requires a regular expression, therefore one single backslash must be escaped by one preceding backslash.

Format the tag-field YEAR only to the first value, that means, make it a single value tag-field ...

$meta(YEAR,0)'\\\\'

Format the tag-field YEAR only to the second value, that means, make it a single value tag-field ...

$meta(YEAR,1)'\\\\'

DD.20140114.2014.CET
DD.20140115.1933.CET

Wouldn't a filter
year HAS \\
be just as nice? This would not need a regular expression and therefore no escaping.
I use the MATCHES operator only if a combined pattern of different patterns has to be found.
Filtering a sub-string of constants can be nicely done with the HAS operator.

Thanks DetlevD!

Filter: NOT "$meta(YEAR,1)" IS "" works for me, but I don't understand why.
Is \\ a common delimiter for multiple values in a field or does this filter work using the position of characters? (I have a lot to learn...)

ohrenkino, I tried year HAS \\ initially, which did not work and led me to post.
Are you saying it should work, or just that it would be nice if it did?

Your filter proposal would also not working, but this works ...

"$meta_sep(YEAR,'\')" HAS "\"

DD.20140115.1921.CET

The doubled backslash '\\' is just a placeholder and a convention in Mp3tag, in order to make the technical zero byte, which is practically invisible to the user, and which works technically as the field separator within a multi-value tag-field, visible to the user.
Other applications may use other replacement characters.

DD.20140117.2233.CET