1x2. 6x9. 1x13. 1xR. It loks like a math problem, doesn't it? Well, just read on and it will all be explained.
You might have noticed that most of the Gundam Wing character's names correspond to numbers in foreign languages. For example, "Quatre" is "4" in French, "Noin" is a variation of the German word for "9", and "Duo" of course comes from the number 2.
Of course, there are hundreds of pairings in Gundam Wing Romance, straight and yaoi (homosexual), so it just helps to learn what number or letter is associated with each character:
1-Heero Yuy
2-Duo Maxwell
3-Trowa Barton
4-Quatre Raberba Winner
5-Chang Wufei
6-Zechs Marquise
9-Lucrenzia Noin
11-Lady Une
13-Treize Khushrenada
R-Relena Peacecraft/Darlain
H-Hilde
D-Dorothy Catalonia
S-Sally Po
C-Catherine Bloom
The numbers or letters with an "x" in between them tell you what couple it's about, for example a site that focuses on a Quatre/Dorothy relationship would be labled "4 (for Quatre) x D (for Dorothy)". Get it? Some other examples include:
1xR-Heero Yuy and Relena Darlain/Peacecraft
11x13-Lady Une and Treize Kushrenada*
6x9-Zechs Marquise and Lucrenzia Noin
*A note of caution: sometimes a "1" is used to refer to Lady Une, like it is with Heero. But if the site is labled 1x13, you can safely assume it's a shrine to the romance of Lady Une and Treize. Otherwise the "1" most likely refers to Heero.
By the way, here's a note: A polite Otaku who's surfing the internet will never flame a site that focuses on a relationship he or she does not agree with. Say you find a 1xR shrine and you don't like Relena. Or you find a site that focuses on a yaoi relationship and you're uncomfortable with yaoi. Or the designer does not allow yaoi and you think that makes them intolerant. If you've got class, you'll simply leave the site, not flame the owner in their guestbook or message board or email or whatever.