Difference between RG174 and RG174AU coax?

A quick google of "coaxial cable number designations" came up with a ton of hits, including :

The current cable designation numbers are at best severely flawed. How are coaxial cables identified? Well technically, only cables that are made to U.S. Government specifications can be marked with the "RG" designation. But in reality, many manufacturers/importers pay little or no attention to the requirements. In those situations, it is up to the purchaser to demand that specific standards be fulfilled. However, as sadly as it is, most of the energy goes into bickering over the cost instead of the quality. And even if the cable carries the designated number, there are often cost cutting activities going on right under your nose. Following find the designated characters legend for cables.

R - Means =3F Radio Frequency

G - Means =3F Government

/U - Means it is a universal application.

Letters that appear before the /U characters (I.e. A, B or C) means a specification modification or revision. For instance, it is common in the CB industry to see the designation RG-58A/U. The original RG-58/U coaxial cable had a solid enter conduct. The "A" modification replaced the solid center conductor with a more flexible stranded center conductor (that is highly recommended for use in mobile installations).

So =3F where is the flaw in the numbering system? The numbering system flaw is that there are no hard character designators that indicate the type or quality of the extremely important shield. Typically, the minimum shielding coverage on "RG" cables used for CB and amateur radio is 78%. That is, 78% of the insulator that encapsulates the center conductor is covered (or shielded) with the over-laid copper braid. Firestik, by choice sets the shielding specification on all their cables to 95%. In contrast, we have inspected cables that end users were using on troubled set-ups that had coverage as low as 52% and their problems were solved by simply upgrading the quality of the coaxial cable.

What does "=3F" mean?

Thanks, Rich

That is an extended character (Unicode)that got (mis)translated by one of the news readers. Happens a lot when cutting and pasting from a Unicode web page.

Thanks WangoTango, that was a really informative answer. I did a lot of checking up on coax specs and changed the stuff I was using.