At face value this seems like a trivial question the TLE's are the input to SGP4, but my question is a little more specific.
Given a TLE, the values are in specific units (eg. argument of perigee is in degrees). The equations listed in space track report #3 do not specify (as far as I can tell - I don't know FORTRAN) what the units the values should be in for computation. Largely this may not matter (degree or radians is simply just a question of using the correct sin/cos) but for some of the equations where the values are multiplied by constants (EG. the equation for D4: has 221 * a0Dash and 31 * s) I'm concerned that the units used may matter!
As far as I can tell the following values are used by SGP4:
First Time Derivative of the Mean Motion divided by two
BSTAR drag term
Right ascension of the ascending node
Argument of perigee
So what conversions must I make before I can start the set of equations outlined in space track report #3 page 10!
I should note that one of the motivations for asking this is the value AE is given as 1 in the constants section toward the end of the document, I can't for the life of me work out why this value has any place in the equations!