[XeTeX] Warning about no Hindi language in Devanagari script

[Steve White]

Hi,

What does this mean?

"Package fontspec Warning:
    Font "Free Serif/ICU/ICU" does not contain language 'Hindi' for
script 'Devanagari'
This warning occured on input line 7."

The document starts with
===========================================
\documentclass[12pt]{book}
\usepackage{fontspec}
\usepackage{longtable}

\setromanfont{FreeSerif}
\newfontfamily{\sk}[Script=Devanagari,Language=Sanskrit]{FreeSerif}
\newfontfamily{\hi}[Script=Devanagari,Language=Hindi]{FreeSerif}
...
===========================================

Both the Hindi and Sanskrit output of the file looks correct, though!