When I read the ingredients in calcium-fortified orange juice, it was
listed as "calcium lactate."  Since "lactate" is a word that
is associated with milk, I wondered if this calcium is milk-derived. Does
anyone know?<

A "lactate" is a "salt,"which in this context means a particular chemical
combination.  Calcium lactate is derived from (a salt of) lactic acid,
which got its name because it was isolated from sour milk, not because it
is itself a dairy product.  Commercial processors normally manufacture it
from other sources in any case.  So calcium lactate is doubly removed from
milk.  It should not be a concern to anyone who is allergic to milk or
Lactose Intolerant.  As an additive, it is classified as GRAS (Generally
Regarded as Safe).

By the way, somebody else wrote >Not all calcium supplements are made
alike.  In fact, most have dairy or
limestone in them.<

I have to assume that "dairy" here incorrectly refers to calcium lactate. 
If not, could somebody please explain what dairy products are in calcium
supplements?

>Also, there is a kosher symbol (the K in a triangle) with no D, DE or M
after it, so it is Parve.  I don't know the "K in the triangle"
organization; I have been researching these groups lately to learn more
about their various tolerance of errors, contamination, and ingredient
interpretation. <

No. Stop. Please.  A great big red warning flag just went up.  Kosher is
NOT the same thing as parve (also spelled pareve). There can be and are
kosher dairy foods.  (New York City has whole stores of them.)  The laws of
kashruth divide all food into  three categories: those with milk, those
with meat, and neutral or parve foods.  (The word comes from the Yiddish,
actually.)  This is a religious prohibition and is absolute.  There is no
such thing as a "little" milk.  So foods that are certified as parve not
only can have no dairy products in them, they can't have any products
derived from dairy in them.  In fact, they can't even be made on the same
equipment that at other times is used for products that do contain milk. 
(This is a good thing, since I know of two cases in the medical literature
in which cross-comtamination caused a child to have an allergic reaction to
a food that was otherwise milk-free.)

So parve is your absolute best guarantee of milklessness.  (So, in the same
way, are kosher foods that contain meat.)  But you must, MUST, look for the
actual word parve (or pareve).  There is no generally recognized symbol
that means the same thing.  So strict is the certification process,
unfortunately, that few companies bother to go through with it.  Many
perfectly milk-free foods are not labeled as parve.  Reading ingredient
lists is still your best bet most of the time.

Hope this helps!
Steve Carper, author of Milk Is Not for Every Body: Living with Lactose
Intolerance
http://ourworld.compuserve.com/homepages/SteveCarper