About reserved characters in an expression
Some characters are reserved for internal use and have a special meaning. For example, as you saw in the expression examples in the previous sections, BIRT Studio uses brackets to denote a data field. The following characters are reserved in BIRT Studio:
' (single quotation mark)
If the name of a data field contains a reserved character, BIRT Studio encloses the reserved character in single quotes (') when you select the data field to use in an expression, for example '['. For example, if the name of a data field is OBSOLETE?, BIRT Studio changes it to [OBSOLETE'?'] in the expression. If you type [OBSOLETE?] in the expression, the dialog box displays an error message. To avoid syntax errors, always select the field from the list in the Calculation dialog box and let the software construct the correct expression.
Figure 3-10 shows an example of the Calculation dialog box displaying a list of data fields, three with reserved characters in their names. The first, second, and fifth fields show both versions of their names, the changed name and the original name with reserved characters, as follows:
[PRODUCTCODE'['4-digit']'] - PRODUCTCODE[4-digit]
Figure 3-10  

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