The command attaches a data frame with a target data. New data records are added after existing data records in the target data, and the operation assumes existing data records in the target data. Naturally, the types and lengths of the data frames have to match, which is also checked.
Example: The example duplicates the Boston housing data.
NDA> load boston.dat NDA> copy boston data2 NDA> attchdat -dout data2 -d boston # Now data2 includes duplicated data records ...