How to parse seconds since epoch as a year value?

[Costello, Roger L.]

Hello DFDL community,

My binary input file contains the number of seconds since epoch for the start 
of a year.

For example, the number of seconds since epoch for the start of 1998 is: 
883612800

I want the XML to just show the year (not month, day, and time).

For example, I want the XML to show this:

<Date>1998</Date>

I thought this would do the job:

<xs:element name="Date" type="xs:dateTime"
    dfdl:lengthKind="explicit" 
    dfdl:length="4" 
    dfdl:binaryCalendarRep="binarySeconds" 
    dfdl:calendarPattern="yyyy" 
    dfdl:calendarPatternKind="explicit"
    dfdl:lengthUnits="bytes" 
    dfdl:binaryCalendarEpoch="1970-01-01T00:00:00" />

But apparently that's not correct.

What is the correct way to do it, please?

/Roger