(imported topic written by Trailsuender)
Source:
Q: name of operating system
A: Linux Red Hat Enterprise Server 5.4
T: 45
How can I get rid of “5.4”?
This is what I need
Target:
A: Linux Red Hat Enterprise Server
For any help many thanks in advance!
(imported comment written by Trailsuender)
OK, after many tries and guesses I found:
Q: substrings separated by ((version of operating system) as string) of (name of operating system)
A: Linux Red Hat Enterprise Server
A:
T: 137
Please, can someone tell me how to remove the second empty “A:”?
I only need the first line and must avoid multiple results.
Many thanks in advance!
(imported comment written by Trailsuender)
OK, it can be done with “whose”:
Q: (substrings separated by ((version of operating system) as string) of (name of operating system)) whose (it contains “Linux”)
A: Linux Red Hat Enterprise Server
T: 119
Or better:
Q: (substrings separated by ((version of operating system) as string) of (name of operating system)) whose (it is greater than " ")
A: Linux Red Hat Enterprise Server
T: 141
Live Long and Prosper! 
(imported comment written by jgstew)
I do like this solution that you came up with by the way, it could be more dynamic and useful in other situations than my suggestion:
(substrings separated by ((version of operating system) as string) of (name of operating system)) whose (it is greater than " ")
(imported comment written by jgstew)
preceding text of last " " of “Linux Red Hat Enterprise Server 5.4”
preceding text of last " " of (name of operating system)