BINARY MODELS  
Summary Reference:  Taylor, J. H., & Weisberg, J. M., ApJ 345:454 (1989)

BT    Newtonian orbit at a given epoch, plus secular changes in the 
      orbital elements and redshift/time-dilation parameter gamma.
      Reference:  Blanford, R., and Teukolsky, S. A., ApJ 205: 580 (1976)

EH    Relativistic model incorporating short-term periodic terms, including
      Shapiro time-delay parameter and non-constant periastron advance
      in the orbital motion, along with the Shapiro time-delay parameter
      References:  Epstein, R., ApJ 216: 92 (1977)
                   Epstein, R., ApJ 231: 644 (1979)
                   Haugan, M. P.  ApJ 296: 1 (1985)
             
DD    Theory-independent relativistic model;  includes treatment of
      short-term periodic terms, Shapiro delay and aberration.
      References:  Damour, T., and Deruelle, N.  Ann Inst. H. Poincare
                     (Physique Theorique) 43: 107 (1985)
                   Damour, T., and Deruelle, N.  Ann Inst. H. Poincare
                     (Physique Theorique) 44: 263 (1986)

DDGR  Variation of DD model in which general relativity is assumed 
      correct, so free parameters are (in principle) only m1, m2.
      Tempo also allows two further free parameters, XPBDOT and XOMDOT,
      to measure deviations from GR values of PBDOT and OMDOT. 
      References:  Taylor, J. H., in General Relativity and Gravitation, ed.
                     M. A. H. MacCallum (Cambridge Univ. Press), p. 209 (1987)
                   Taylor, J. H., & Weisberg, J. M., ApJ 345:454 (1989)

H88   Re-parameterized EH model 
      Reference:  Haugan, M. P. 1988.  Preprint.  (See Taylor & Weisberg 1989.)

BT+   BT model with nonlinear periastron advance.

DDT   DDGR modified to test two-parameter tensor-biscalar theories
      Reference:  Taylor, J. H., Wolszczan, A., Damour, T., and Weisberg, J. M.
                    Nature, 355: 132 (1992)

MSS   Model for main-sequence/pulsar binaries.
      Reference:  Wex, N., astro-ph/9706086 (1997).

ELL1  Model for low eccentricity orbits using Laplace parameters
      (EPS1=e times sin(omega), EPS2=e times cos(omega)) instead of e, omega.
      Reference:  Wex, N., unpublished.

BT1P  BT model with two orbits:  the first may be relativistic, the 
      second must be Keplerian

BT2P  BT model with three orbits:  the first may be relativistic, the
      second and third must be Keplerian 

BTX   BT model with orbital motion expressed in frequency rather than
      period.  Orbital frequency may vary, either through instantaneous
      jumps in binary frequency (jump size FBJ_x at time TFBJ_x) or through a
      Taylor expansion around T0 (FB_x is x'th derivative of binary 
      frequency).  Orbit size may also be written as a taylor expansion
      (XDOT_x is x+1'th derivative of X=A SIN I)
      Reference:  Nice, D., unpublished

BTJ   BT model with addition of up to 8 epochs at which steps in binary 
      parameters and pulse phase can be inserted and solved for. (RNM)

The following table summarizes the parameters used by each model.  An 'x'
indicates a parameter fully implemented.  An 'o' indicates the parameter is
used at a fixed value, but cannot be fitted.  A '*' indicates the parameter
is used only to calculate other binary parameters, and is then ignored.


           BT   EH    DD    DDGR    H88    BT+    DDT    MSS   ELL1    BTX  BTJ
A1          x    x     x      x      x      x      x      x      x      x    x
E           x    x     x      x      x      x      x      x      *      x    x
T0          x    x     x      x      x      x      x      x      *      x    x
PB          x    x     x      x      x      x      x      x      x      *    x
OM          x    x     x      x      x      x      x      x      *      x    x
TASC        *                                                    x
EPS1        *                                                    x
EPS2        *                                                    x
FB          *    *     *      *      *      *      *      *      *      x
FB_1        *    *     *      *      *      *      *      *      *      x
FB_x                                                                    x
OMDOT       x    x     x             x      x             x      x      x    x
OM2DOT                                                    x             x
XOMDOT                        x
PBDOT       x    x     x             x      x      x      x      x      *    x
XPBDOT                        x
GAMMA       x    x     x             x      x             x             x    x
MTOT                          x                    x
M2                     x      x                    x      x      x
SINI             x     x             x             x      x      x
DTHETA                 x                                  x
XDOT        x    x     x      x             x      x      x      x      x    x
X2DOT                                                     x             
XDOT_x                                                                  x
EDOT        x    x     x      x             x      x      x      x      x    x
EPS1DOT                                                          x
EPS2DOT                                                          x
DR                     o                           o      o    
AFAC                          o
A0                     o                           o      o      o
B0                     o                                  o      o
BP                                                 o
BPP                                                o
BPJEP_x                                                                      o
BPJPH_x                                                                      x
BPJA1_x                                                                      x
BPJEC_x                                                                      x
BPJOM_x                                                                      x
BPJPB_x                                                                      x