Dress Size - Standard vs. Catalog

The more I read, the more confused I am getting. It seems that dress sizes really have no standard. There was one which is used on the back of sewing patterns, but this is not what is used in the stores anymore. This is called a catalog size, and seems to vary a bit.

Some links:

• NIST's Role, Standardization of Women's Clothing Sizes - NIST
• kids sizes estimator.
• US standard clothing size - Wikipedia
• Free Standard Clothing Sizes Measurements Chart from Fiber Images (I am not sure if this is catalog or the old one).
• Overstock.com Apparel Sizing Guide