The interpolation code `interp_typ` used in the `ENDL` system
specifies the type of interpolation to be used for the data on energy
and cross section. Only the values
= 0 and 5 are
used.

**= 0:**- Linear-linear interpolation. This is used for all but incident gammas.
**= 1:**- Piecewise constant (a histogram).
**= 2:**- Linear-linear interpolation.
**= 3:**- Linear-log interpolation (logarithmic in
*x*). **= 4:**- Log-linear interpolation (logarithmic in
*y*). **= 5:**- Log-log interpolation. This is used only for incident photons.