What is the proper way to describe in DFDL an input field that holds a boolean value?

[Costello, Roger L.]

Hello DFDL community,

The specification for my input file says this about a field:

Name: isSimulation
Type: Byte
Description: always set to 0 (false)

I tried describing that input field using this DFDL:

<xs:element name="isSimulation" type="xs:boolean"
                dfdl:binaryBooleanTrueRep="1"
               dfdl:binaryBooleanFalseRep="0" /> 

Parsing the 1-byte input field results in this error message:

[error] Parse Error: Insufficient bits in data. Needed 32 bit(s).

Eek!  32 bits?

Why are 32 bits needed for the xs:boolean datatype? It seems like 1 bit should 
be enough.

What is the proper way to describe in DFDL the input field?

/Roger