Re: Compute Date Duration -- MI400

OK. Here's what some experimentation shows:

CDD will calculate a duration between character format dates. This isconsistent with the CDD instruction description which states thatoperands 2 and 3 must be character scalars. That means the only validdate types for operands 2 and 3 are:

        USA
        ISO
        EUR
        JIS
        System Internal Date (Scaliger number)
        *MMDDYY
        *DDMMYY
        *YYMMDD
        *YYDD
        *YYYYDDD

Default separators are required for the first 5 but the last 5 can haveany separator or no separator as long as the DDAT correctly describesthe separator. If the specified date value does not match the DDAT thenMCH1222 will occur.

NOTE:- The scaliger number specified for the System Internal Date typemust not exceed the end date of the Calendar (else MCH1221) nor must itbe earlier than the start date of the Calendar (else MCH1224).

CDD does not support other date formats so if you have dates in otherformats (e.g. packed or zoned numeric) you must first convert them to aformat that CDD does support.

Most DDAT errors will cause MCH1867 but some will cause MCH5601. Errorsin the first 58 bytes of the template will cause MCH5601.

CDD always returns a Date Duration. That is an 8,0 packed decimal valuein the form YYYYMMDD which is interpreted as YYYY years, MM months, andDD days. Specifying any other format type will result in MCH5601.

I also discovered that if the Calendar Table is not allowed for aparticular format type (such as Date Duration) then if you specify zerofor the Calendar Offset you can omit the Calendar Table entirely.

However the Era Table must be present (and set to X'00' for a DateDuration) otherwise MCH1867 is sent with reason code 19

Further the DDAT_List_Size (as distinct from the DDAT_Length which canbe anything including zero) is validated for being greater than 0 butotherwise seems to tolerate incorrect values. Not that I'm advocatingdoing so but it is interesting. When it is zero the #cfdate module getsthe DDAT number wrong in MCH1867. It shows 16448 which is the value ofan uninitialised BIN(2).

So that just leaves the question of how to convert a Date Duration to aLabelled Duration and that can be done with maths.

I haven't found an MI instruction that will generate a LabelledDuration. They seem to be valid only as input to the various INC andDEC instructions.


Regards,
Simon Coulter.
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