13.3.1.2.3 Expression Pane
When choosing an Expression to act as the source for your Allocation rule, the expressions available to you are limited to those built upon the table you selected in the For pane.
Note:
Expressions may not be used with Management Ledger tables but will be supported in a future release.Figure 13-11 Expression Pane

Note:
Currency conversion for expression in the source is not supported as the expression can be defined on a combination of multiple columns having balance/non-balance columns.