This is purely diagnostic. It prints warnings in either of 2 cases. 1) observed data has values that are not in the value_old, or 2) that value_old has values that are not in the data.
checkValue_old(x, value_old, xname, diagnostic = FALSE)
a variable, either character or factor
a vector of old values for which we are checking
character string to use for x's name when printing output
prints messages about variables if TRUE
Paul Johnson <pauljohn@ku.edu>