Vehicle harness question

Celsior - (H15 / 8 ~ 18 / 9) (UCF31)
Celsior - (H12 / 9 ~ 15 / 7) (UCF31)

I'm looking at Datasystem harnesses and those are two options for the UCF31.  What does the "H" number range signify?  I've seen it a lot on Japanese part descriptions.

This got answered over on CL.

[quote]
Japan use Western years (i.e. 2001, 2004 etc..) and Emperor's years.
Every time we have a new emperor, it will start over with a new heading.

So now, "H" represent "Heisei". (Yr 2010 = H22. )

H12 = Year 2000.


For
UCF31 Before M/C, Use Harness # H-087D
UCF31 After M/C, Use Harness # H-087E[/quote]

word. i thought it was how long the model had been in production but it never quite added up.