The transmission of electronic product catalogs using e-business standards belongs to the first and most common applications of XML in B2B e-commerce. Suppliers create electronic catalogs in standardized formats and transfer them to their customers. Eventually the receiving enterprises import the data into e-market places and e-procurement systems. In both cases a transformation of relational data structures to XML documents (or in reverse) is necessary. During the transformation process not only the data structures but also the power of the data modeling concepts of the respective catalog standards must be considered. Based on this knowledge the conversion could be made easier or partly automatically. This paper examines, to what extent real-world XML catalog standards make use of formal specification languages. For that purpose the relevant modeling concepts are viewed and applied to selected standards. The result is a close look at the common practice of using XML schema languages in B2B catalog standards.