2.341.6.12 Restrictions on Use of Global Collections

The Fields, Parameters, ReportItems, and Globals collections have restrictions on the contexts in which they can be used in expressions. The following table specifies where these global collections can ("Yes," or with restrictions specified below) or cannot ("No") be used.

Usage Context	Global collections
	Fields	ReportItems	Parameters	PageNumber TotalPages	DataSource DataSet	Variables	Scopes
PageHeader or PageFooter	Yes	Yes*	Yes	Yes	Yes	Yes	No
Body	Yes**	Yes***	Yes	No	Yes	Yes	Yes**********
ReportParameter	No	No	Yes****	No	No	No	No
Field	Yes	No	Yes	No	No<193>	No	No
Query Parameter	No	No	Yes	No	No	No	No
Group Expression	Yes	No	Yes	No	Yes	No	No
Sort Expression	Yes	No	Yes	No	Yes	Yes*****	No
Filter Expression	Yes	No	Yes	No	Yes	Yes*********	No
Code	No	No	Yes	No	No	No	No
Report.Language	No	No	Yes	No	No	No	No
Variables	Yes	No	Yes	No	Yes	Yes******	No
Aggregates	Yes	Yes*******	Yes	Yes********	Yes	No	No
Lookup LookupSet	Yes	Yes	Yes	Yes	Yes	No	No***********

* MUST NOT contain more than one report item reference.

** If an expression in a non-detail section refers to a field that is not in the group expression for the group (or any ancestor grouping scope), which specific value is used is not defined. The expression SHOULD use the First() and Last() aggregate functions.

*** MUST NOT contain report item references other than those in the current or ancestor scope.

**** MUST NOT contain parameter references to subsequent parameters.

***** Variable references in sort expressions can appear in TablixMember, DataMember, and ChartMember elements. Variable references MUST NOT appear in DataRegion.SortExpressions.

****** MUST NOT contain variable references other than those in the current or ancestor scope.

******* MUST NOT be used outside a page header or page footer.

******** MUST NOT be used outside report item aggregates in a page header or page footer.

********* Variable references in filter expressions can appear in TablixMember, DataMember, and ChartMember elements. Variable references MUST NOT appear in DataRegion.Filters or DataSet.Filters.

********** MUST NOT be used for ReportItems outside DataRegion.

*********** can only be used in the Source expression of a Lookup function.

Note that, because references to items in global collections can be dynamic, such as in "=ReportItems(Parameters!Param1.Value)", all error checking occurs both during report validation (to catch static disallowed references) and during report execution (to catch dynamic disallowed references).

Cyclic expressions (such as TextBox1=TextBox2+1; TextBox2=TextBox1+1) are treated as non-critical errors.