Re: Unsafe Levels of Selenium Found in Dietary Supplements

d refers to dextro or right handed
l refers to levo or left handed
dl refers to both being present.

This is not as significant as the positional aspect of the various forms:

a or alpha
b or beta
d or delta
g or gamma

See
http://en.wikipedia.org/wiki/Tocopherol
for a more complete illustration.

Most synthetic tocopherol is the a or alpha form and is what most people take. Ideally, you should take mixed tocopherols from a natural source. I add the g or gamma form to my supplementation every few days.