By default, there are no order constraints on missing value estimates. The two-letters value must consist of two letters in alphabetical order. Note that other less computationally intensive error checking is always performed. They do not contribute to the analysis but are scored and transformed as supplementary or passive observations. If you want to create a permanent SAS data set, you must specify a two-level name.
Small values make the method run more slowly and with more numerical accuracy.
If such a variable is found, it is used to provide the initial values for the first iteration. The final transformation is a member of the transformation family defined by the original variable, not the transformation family defined by the initialization variable. The names of the transformed variables in the output data set correspond to the names of the original variables in the input data set. By default, scores are not included. When a variable is linearly transformed, the final variable contains the original nonmissing values and the missing value estimates.