trim(string) does not work

trim(string) → the compiler does not recognise the statement. If someone does get it to work, please post an example. I could not find anything on the Internet that might point out why compiling the statement produced an error.

program trim_string_works
character(len=30) name
name = 'Casper the Jack Russell       '
write(6,*)      len(name)
write(6,*)      len(trim(name))
write(6,'(A)') '123456789012345678901234567890'
write(6,'(2A)') name,'X'
write(6,'(2A)') trim(name),'X'
end program trim_string_works 

A better example:

program trim_string_works
character(len=30) name, breed
name = 'Casper       '
breed = 'Jack Russell terrier'
write(6,'(A,1X,A,1X,A)') name, 'is a', breed
write(6,*)
write(6,'(A,1X,A,1X,A)') trim(name), 'is a', breed
end program trim_string_works


Casper                         is a Jack Russell terrier

Casper is a Jack Russell terrier

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Thank you for your very explanatory response to my query! Patrick