Field Masking is used to control the display or format of information loaded into specific fields. Field masking can be used to control the precision of certain fields (i.e. pricing in whole dollars or to 2 decimals) and it can also be used to make data easier to read (i.e. (239) 283-9710 x204 in a phone number field).
Field masking is controlled using the Field Mask Setup program located on the System Administration - Param/Control files Menu.