How to add a parent element when read in text file using XSLT 2.0?

I have to use XSLT 2.0 to read in a text file and output an XML. The input text file is like:

Start:000,A:123,B:234,C:33,End:99,Start:03,A:123d,B:234s,End:992,Start:a00,B:234,C:33,End:99

And the desired XML output is like:

<File>
<Rec>
    <Start>000</Start>
    <A>123</A>
    <B>234</B>
    <C>33</C>
    <End>99</End>
</Rec>
<Rec>
    <Start>03</Start>
    <A>123d</A>
    <B>234s</B>
    <End>992</End>
</Rec>
<Rec>
    <Start>a00</Start>
    <B>234</B>
    <C>33</C>
    <End>99</End>
</Rec>

I have difficulty grouping elements from "Start" to "End" and adding a parent element "Rec" to it. Any suggestion? Thanks a lot!