My built-from-scratch system was also a Linux OS. Perhaps replace "is" with "provides" or "is one way to get" or something?
While being correct this addition does not ring well with the sentence following it:
There is free software and there is source-available software (like Solaris). One should not imply that these are the same.
That nonwithstanding, compliments to Dmerrill for incorporating LD material from LOS! --Robbe