and came up with this in a google search.
According to Wikipedia, Corning's responsibility extends to this formality:
When trademarked as PYREX® (all UPPER CASE LETTERS plus, in the USA, a trademark notice comprising a capital R in a circle) the trademark includes clear, low-thermal-expansion borosilicate glass used for laboratory glassware and kitchenware, plus other kitchenware including opaque tempered high-thermal-expansion soda-lime glass, pyroceram, stoneware, and metal items See. e.g.,http://www.amazon.co.uk/s?index=kitchen-uk&field-keywords=pyrex.
European trademark usage differs from American and the encircled "R" is not present on European PYREX items.
When trademarked as pyrex® (all lower case letters plus a trademark notice comprising a capital R in a circle) the trademark includes clear tempered high-thermal-expansion soda-lime glass kitchenware, plus other non-glass kitchenware, made by World Kitchen. See, e.g.,http://www.amazon.com/s/ref=bl_sr_kitchen?node=1055398&field-brandtextbin=Pyrex
I actually did not know anything about this so now I know what to look for (I think).