This is an error in the Documentation, we'll ensure it gets resolved. The correct values are True or False.
The correct value can be enforced with the Properties Definition file.
If the Regular Expression value is "True|False" then the punctuation should be checked when entering the property value and the following warning is in the output window for non-valid values
Illegal property value, the regular expression for this property value is: True|False
There are exceptions for example; DxDatabook, does not observe these rules. How were you entering the data?