Select statement "containing" is confusing

[HaukeBartsch]

If a select statement contains: "BolusAgent containing Dotarem" the select statement might not work, even if the tag contains the string "14ml of Dotarem". The issue is caused by "containing" actually performing an "equal" operation.

Why? Tags in DICOM might contain an array of values. Something like "ORIGINAL/PRIMARY" which is an array with 2 strings. The "containing" operation of select will match your search string with each of the 2 strings in the array. So the meaning is "is any of the array elements equal to the search term Dotarem". In the above example there is only a single array element ("14ml of Dotarem"). That entry does not equal the search term so the matching fails.

Instead use the operation "regexp" which can perform this check if a string contains another string with:
BolusAgent regexp ".Dotarem."

Should we rename "containing"? Should we produce a warning if containing is used with a single string instead of with a value multiplicity of > 1?