Field Mask Processing
Field mask processing is available within source data identifiers of the data element and within disguise rules. Field mask allows selected characters of the value to be processed. Each position of the mask corresponds to a character or digit in the source value. When the processing type is a number, the positions of the field mask only correspond to the digits of the number, there is no position in the mask for the decimal point or the negative sign.
A field mask provides a way to limit which positions of a field are processed. The values defined in the field mask correspond to the characters in the field being processed. The field mask can contain all Ys and blanks, all Ns and blanks, or a combination of Ys and Ns without any blanks. Y means process the character, N means do not process the character, and blank means do the opposite of the values entered.
When a field mask is used, the values that correspond to the Y positions in the field mask are processed as if those positions are the entire field value. Only those positions are available to the action where the field mask is defined. When disguised data is returned to a field with a field mask applied, only the positions marked Y are replaced. Any positions marked N remain unchanged. The field mask that is entered will be interpreted to process each incoming value.
When the field mask is all Ns and blanks, all characters within the incoming value that do not correspond to the Ns are processed. Each character that corresponds with a blank in the field mask is processed. If the incoming value is longer than the field mask, all characters beyond the length of the mask are processed. Only the characters that correspond with the Ns of the field mask are not processed; everything else is processed.
When the field mask is all Ys and blanks, or a mixture of Ys and Ns, only characters within the incoming value that correspond to the Ys are processed. Characters that correspond with a blank in the field mask are not processed. If the incoming value is longer than the field mask, all characters beyond the length of the mask are treated as Ns and are not processed. When the field mask is longer than the incoming value, only the positions within the field that correspond to the Ys within the mask are processed. Only the characters that correspond to the Ys within the mask will be processed. If the incoming value is shorter than the mask, the value is not padded based on the length of the field mask. For example, if a field mask of YYY is applied to a value of AB, only the AB is processed and no invalid data warning is logged.
Processing Types
The processing type for a data element determines the way in which the field mask is applied. Do not define a field mask for a data element that uses date processing because there is no way to mask specific positions of a date.
When the processing type is number, the field mask is applied right to left. Field mask positions only correspond to the digits of the number. The sign and decimal point within the number are not mapped to positions in the field mask. The resulting value will be unsigned and have no decimal positions. Field mask does not include any processing for decimal alignment. If the number of decimal positions must be consistent, the processing options within the data element should be used to specify the number of decimal positions before applying the mask.
When the processing type is anything other than number, the field mask is applied left to right. Field mask positions correspond to the characters of the value.
When the field is graphic (DBCS), the field mask still maps to the characters, but one position of the entered mask is associated with two positions of the source field.
Masking within Rules
Field masks can be used within disguise rules either within the rule action or within the rule logic. The field mask can apply to either a data element or a variable.
Within a rule action, you can set the field mask by first selecting the data element or variable and then clicking in the Field Mask column for that item. The field mask field is not enabled for editing until the data element or variable is selected.
A field mask within the rule logic is defined from the expression builder. The mask positions will be defined as part of a masking function so that the field mask can be applied during condition checking. When a field mask is used, only the values that correspond to the Ys in the field mask are processed. Any position specified as Y in the field mask that is beyond the length of the incoming value is ignored and the incoming value is not padded.
The administration function for defining translate tables includes the definition of access paths, which represent the ways in which a translate table can be accessed. When the access requires a source field, a field mask can be defined for the field. This definition is the same as the field mask definition within the disguise rule action.