Saving empty string value

Can anyone suggest a fix to this?

The intent of the highlighted lines is that any subsequent run use the same input value of e.g. %artist% as the first. The effect is that where the input value was an empty string, it doesn't. It uses the value created by the liens below.

The action group needs the tag-field ARTIST to be exist, having any value?
Then preset the Filter: ARTIST PRESENT

... or ...
Preset CJJORIGTITLE with a standard text, when the tag-field TITLE is empty ...
Format value "CJJORIGTITLE": $if2(%CJJorigtitIe%,$if2(%TITLE%,'set any standard text here'))

DD.20140818.1732.CEST

No. It is needed to work if ARTIST exists with any value or if ARTIST does not exist.

(By standard test I presume you mean some arbitrary but reserved string.)

OK... and I guess then when I fetch the field, translate the standard text back to empty e.g. $regexp(%title%,'^set any standard text here$',)

I'll try it. Thanks D.

A string of one or more spaces may work.

DD.20140819.0938.CEST

For the standard string to work it must be reserved i.e. never occur as the actual incoming value of a field. So I think just spaces is risky. Best is perhaps e.g. "&^"£&"^&£^"&^£")(*"

Could be just some character/s from the set $char(1)..$char(31)
... or $char(9216)
... or $char(9248)
... or $char(9250)
... or $char(9251)
... etc.

DD.20140819.1424.CEST

Thanks D.

from the set $char(1)..$char(31)

Mp3tag shows improbable glyphs ...

... or $char(9216)
... or $char(9248)
... or $char(9250)

and hollow boxes...

... or $char(9251)

but there shows ␣ , so I think that's the safest. It tests OK on WMA, but I don't know about other formats.

BTW, for anyone like me looking for tricks to format a Creative ZEN display: all those characters are successful in affecting sort order, but appear as hollow block, rather than invisible. If anyone finds a sort-affecting character that is invisible, please do tell!