With only one filed, you only can add the text explaining the rule, IE:
Here, I used the ; sign to separate concepts, I used the : sign to separate Identifiers from their values and used the - sign to separate the bounds.
You can create the filed content easely by concatenating the right words, separators and values.
You can 'decript' the field using the string Split() function 3 times. The first using the ; as separator to get the Keywords and the values, each in a separate string (3 strings in this case).
The second, for each KeywordAndValue string obtained, you can use the Split() function with the : as separator to obtain 2 strings: the Keyword and the Value
The third, for those kywords that have bounded values, you can use the Split() function again with the - as separator, to obtain the lower and upper values.