The CEO of Pro Travel Network, Paul Henderson, said he is fed up with industry conversation where speakers routinely use the terms "card mill" or "MLM" to criticize or smear competitors they don’t like.

Pro Travel Network uses multilevel marketing (MLM) to recruit travel agents, but that does not make these agents illegitimate, Henderson said. In fact, there is no universal agreement as to what constitutes a legitimate travel agent, he said.

In an open letter, Henderson called for a "universal guideline as to exactly what are the qualifications of an agent."

"How about we concentrate on fixing the rules of the game to ensure a fair playing field for all?" wrote Henderson.

The term "card mill" has no real meaning, Henderson said.

"We have no right to [keep] a company from issuing its own ID cards in an industry that has no uniform guidelines," Henderson wrote. "Why can't Host Agency X issue a card of its own, to its own agents, with its own guidelines? ... Shouldn't the acceptance of a particular credential be left to the accepting supplier, absent any uniform guideline?

"And if abuse is found, that supplier can terminate said agency, as Perillo did [in the case of YTB]. ... Who are we to pressure other suppliers? Let's worry about our own businesses."

Henderson also addressed the negative perception of MLMs.

"MLM has become just another buzzword created to label those we don't like," he said. "Is there anyone today who sees Mary Kay as a bad business model? Is there anyone out there who hasn't eaten from Tupperware? Avon is a household name."

Henderson wondered why a traditional company can sell a home-based product with training and other support tools, but "if an MLM does it, it is no longer a valid product."

Henderson said he is not promoting or defending card mills and MLMs, but redirecting the conversation to the "real issue."

"How about a forum on industry regulation and defining what an agent is or isn't?" he said. "If a person has not satisfied certain requirements, then he or she is not called a travel agent, or maybe [there should be] a system that rewards in degrees of agent proficiency or sales."

Until there is an agreed system of guidelines, people should "stop the witch hunts," he wrote.

"Stop wasting my inbox with this nonsense," Henderson said.

Click here to read Henderson's open letter.