What Were the Criteria For “Professional” Audio Cassettes?

It’s a good question. What, exactly, entitled a manufacturer to brand the word “Professional” onto an audio tape? Or to describe it as “professional quality” in blurb? Was there a bench test that defined a standard of performance, above which the cassette attained suitability for professional use?

1993 PMD Magnetics Professional Audiocassette C15

Here’s a cracker from the 1990s – a PMD Magnetics Professional Audiocassette, which I think would probably have been manufactured in 1993 – the year I bought it. The ‘Professional’ designation hints at something fairly magnificent, so you’d expect at least a high bias Type 2 tape – if not a Type 4 metal job. However, this is in fact a normal bias Type 1, with a ferric formulation.