The James Webb Space Telescope is a large infrared observatory with a segmented primary mirror, part of the
Optical Telescope Element (OTE), and four science instruments supported by the Integrated Science Instrument Module
(ISIM). We present the calibration plan for the ISIM Test Platform (ITP) which replicates the ISIM-to-OTE interface: to
calibrate the location and orientation of metrology features at ambient and cryogenic environmental conditions, to verify
that ITP behavior (deflection under load, warm-to-cold alignment shift) can be modeled, predicted, and tested, to prove
that the ITP is stable (upon repeated cryogenic cycles, and after loading and handling), and to calibrate the relationship
between the Master Alignment Target Fixture and the ITP at ambient and cryogenic conditions.