For the calculation models listed in the following table, the environment in which the system operates has a considerable effect on prediction results. Because environment choices vary from model to model, you should scrutinize the environments supported by models prior to deciding which to use. For example, Telcordia models do not support naval environments. Consequently, it would not be the model of choice for a system that operates on a naval ship. In the referenced topics, both the environments supported by a model and the codes assigned to environments are listed.

When a model that supports environments is selected in an assembly’s Calculation Data pane, Environment and possibly Environment, dormant are shown. In the field name for Environment, the one or more models whose environments are included in the attached list are shown. For example, when a MIL-HDBK-217, Telcordia, or Bellcore model is selected, Environment, 217 / Telcordia is the field name. For these models, choices for Environment, dormant are: Airborne, Ground, Naval, and Space.

MIL-HDBK-217, Telcordia, Bellcore, 299, and HRD5 models support custom environments. You can insert custom environments that you want to use for these models in Prediction Values Library files. For more information, see Prediction Values Library Files. Additionally, you can insert a custom environment from a System file by directly entering it for Environment in the Calculation Data pane for an assembly. For more information, see Inserting a Custom Environment or Quality Level from the System File.