What's the deal with the subscript X in pharmacy names?

Factual Questions
1

Everyone pharmacy I’ve seen has an R[sub]x[/sub] in the name somewhere. What does it mean?

[sub]fixed coding - DrMatrix[/sub]

2

Damn, forgot to use the UBB brackets. Could a mod please fix that for me?

[sub]x[/sub]

3

Rx is a symbol derived from the Egyptian eye of Horus. See http://www.straightdope.com/mailbag/mrx.html