Slightly trickier than we thought.

An initiative by Revenue Science to standardize elements of behavioral ad targeting was met with mixed feelings.

Revenue Science kicked off the program by sponsoring a coalition of industry players that would standardize terminology and measurement in behavioral targeting. Each firm currently uses its own set of definitions and standards, making the buying process tricky.

Making standards uniform will give media buyers a sense of what to expect, thereby inviting more investment into behavioral targeting. The first organization to accomplish this goal will also be perceived as a thought leader in the arena.

One holdout from the initiative is AOL's Tacoda. The firm says it will comply with standards set by the FTC and/or National Advertising Initiative, but it will not participate in Revenue Science's sessions.

A company spokesperson says Revenue Science's standards will be almost impossible to agree upon.