Why Does The Drug Description For Paxil-CR (paroxetine HCl) State

Why does the drug description for Paxil-CR (paroxetine HCl) state that it has a chemical structure unrelated to other SSRI's or to tricyclic, ttracyclic or other available antidepressant or antipanic agents? This phrase does not occur in the drug description for Paxil. The controlled release states that one layer of the tablet consists of a degradable barrier layer and the other contains the active material in a hydrophylic matrix. There is some crossover in the inert ingredients, but the coloring agents are variable.