complex numbering problem

Hi all,

I'm fairly new to XSL but after a couple of hours of googling and
thinking about how to structure my xsl file differently I came here in
the hope that someone can help me not using saxon:assign (I already
learned that this would be a bad thing - but to be honest, I also cannot
get it to work with my Oxygen 9.3 ;-)

I'm using Oxygen 9.3 under SuSE Linux 10.0. XSL 1.0, Saxon 6.5.5

The problem is as follows: I want to transform one kind of XML files
into another kind using XSLT.

This is how (the relevant part of) my source file looks like:

<root>
<layer l-id="l01">
<meta m-id="m01">
<desc><name>layer-interpretation</name><val>abc</val></desc>
<desc><name>layer-type</name><val>some_type</val></desc>
</meta>
<event e-id="l01-001" start="0" end="17.499806"/>
<event e-id="l01-002" start="17.499806" end="17.524455">XYZ</event>
<event e-id="l01-003" start="17.524455" end="113.487545">XYZ</event>
<event e-id="l01-004" start="113.487545" end="113.554857">XYZ</event>
<event e-id="l01-005" start="113.554857" end="113.94197">XYZ</event>
<event e-id="l01-006" start="113.94197" end="114.1085">XYZ</event>
</layer>
<layer l-id="l02">
<meta m-id="m02">
<desc><name>layer-interpretation</name><val>xyz</val></desc>
<desc><name>layer-type</name><val>some_other_type</val></desc>
</meta>
<event e-id="l02-001" start="0" end="17.7997">XYZ</event>
<event e-id="l02-002" start="17.7997" end="112.409813">XYZ</event>
<event e-id="l02-003" start="112.409813" end="112.763921">XYZ</event>
<event e-id="l02-004" start="112.763921" end="113.570947">XYZ</event>
</layer>
<!--some more layers-->
</root>

This is how I want my target file to look like:

<time_order>
    <time_slot time_slot_id="ts1" time_value="0"/>
    <time_slot time_slot_id="ts2" time_value="0"/>
    <time_slot time_slot_id="ts3" time_value="17.499806"/>
    <time_slot time_slot_id="ts4" time_value="17.524455"/>
    <time_slot time_slot_id="ts5" time_value="17.7997"/>
    <time_slot time_slot_id="ts6" time_value="112.409813"/>
    <time_slot time_slot_id="ts7" time_value="112.763921"/>
    <time_slot time_slot_id="ts8" time_value="113.487545"/>
    <time_slot time_slot_id="ts9" time_value="113.554857"/>
    <time_slot time_slot_id="ts10" time_value="113.570947"/>
    <time_slot time_slot_id="ts11" time_value="113.94197"/>
    <time_slot time_slot_id="ts12" time_value="114.1085"/>
</time_order>

That means, I want every time index (even duplicates, because I need
them later on) in a separate time_slot element. The time_slot elements
should be sorted by the time_value in ascending order and should get a
unique id, also in ascending order. I just cannot get the XSL structured
in such a way that both attributes are in order. It's always one or the
other, but never both. Or when I get both in order, I have duplicate
time_slot_id's instead.

My latest attempt looks like this:

<xsl:template match="event" mode="timeslots">
    <time_slot>
        <xsl:attribute name="time_slot_id">
            <xsl:text>ts</xsl:text>
            <xsl:number level="any" value="position()"/>
        </xsl:attribute>
        <xsl:attribute name="time_value">
            <xsl:value-of select="@start"/>
        </xsl:attribute>
    </time_slot>
    <xsl:if test="count(following-sibling::event)=0">
        <time_slot>
            <xsl:attribute name="time_slot_id">
                <xsl:text>ts</xsl:text>
                <xsl:number level="any" value="position()"/>
            </xsl:attribute>
            <xsl:attribute name="time_value">
                <xsl:value-of select="@end"/>
            </xsl:attribute>
        </time_slot>
    </xsl:if>
</xsl:template>

With this, both attributes are (almost, but not quite - why?) in order,
but I get duplicate IDs for the "end" attributes. The result looks like
this:

<time_order>
...
<time_slot time_slot_id="ts1727" time_value="113.487545"/>
<time_slot time_slot_id="ts1728" time_value="113.554857"/>
<time_slot time_slot_id="ts1729" time_value="113.570521"/>
<time_slot time_slot_id="ts1729" time_value="114.10741400000001"/>
<time_slot time_slot_id="ts1730" time_value="113.791077"/>
<time_slot time_slot_id="ts1730" time_value="114.10859000000001"/>
<time_slot time_slot_id="ts1731" time_value="113.94197699999999"/>
<time_slot time_slot_id="ts1731" time_value="114.10859000000001"/>
</time_order>

The only idea I have to fix this, is a variable which I increase every
time I enter the if block and which is added to position() to form the
ID. But XSL has no variables and so I'm kind of stuck.

I hope one of the XSL experts out there can help me.

kind regards
Alex