When implementing Formula Engine code - depending on the context - there are certain built-in variables available to you. In this article I am listing the built-in variables you are most likely to use:
| Variable | Usage |
|---|---|
| $DATA | The value to be returned or stored. |
| $PREVDATA | The previous value. E.g. in a store() function, $PREVDATA will hold the previous value. And $DATA the value to be stored (giving you a chance to examine and change it). |
| $FIELD | The attribute id, e.g. in a select() function of a derived attribute. |
| $LISTID | The list ID, e.g. in a select() function of a derived list. |
| $SYMBOL | The symbol / ADO ID in the context of many functions: select(), store(), validation functions etc. |
| $STATUS | The status to be returned or stored. |
| $TREEID | The datafile tree ID, e.g. in the select function for a derived tree. |
For a complete list of available built-in variables, please consult the AC Server Manual.