What does this term mean (language/argot)

[fluidistic]

In several papers I read "L1₁ type Co-Pt ordered alloy" (see http://jap.aip.org/resource/1/japiau/v103/i7/p07E114_s1?isAuthorized=no , http://iopscience.iop.org/1742-6596/200/10/102002, http://www.sciencedirect.com/science/article/pii/0022024893903757).
What exactly is meant by L1₁?
Google seems to lead me only on a few of these papers.

 

[tiny-tim]

hi fluidistic!

i think it means rhombohedral,

see http://cst-www.nrl.navy.mil/lattice/struk/l1_1.html

 

[fluidistic]

hi fluidistic!

i think it means rhombohedral,

see http://cst-www.nrl.navy.mil/lattice/struk/l1_1.html

Thank you very much tiny-tim! I've plotted the position of these atoms in VMD to visualize them in 3d.
Another question for anyone who knows: when they say

Ag composition is around 50 at. %

what do they mean by . %? Do they simply mean that there's 50% of Ag in the sample? This looks a rather strange way of saying it.

 

[tiny-tim]

Ag composition is around 50 at. %

i'm guessing … could "at." be short for "atoms"?

 

[Useful nucleus]

at. % denotes percentage based on the number of atoms (also moles). While w% denotes percentage based on the weight.

 

[fluidistic]

Thank you infinitely guys. I wouldn't have figured it out on my own.