XSL to Parse and Re-order XML Nodes - xslt

Question

I need assistance with creating a XSL stylesheet to parse data and re-order based on values within certain nodes. My original XML is being exported by a roster program in a undesirable structure which is causing issues when converting to JSON.
This is a Fire Department roster that will be converted into JSON to be processed by Station Status Boards. I'm looking to format the XML so that when converted into JSON each Station has a crew list. I've attempted to create a XSL without success. I have zero background in XSL (Fire Fighter).
Section of Original XML:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Data>
<Date>2019-05-07-07:00</Date>
<Headers></Headers>
<Records>
<Record>
<RscPayrollIDCh>12345678</RscPayrollIDCh>
<RscEmployeeIDCh>12345678</RscEmployeeIDCh>
<RscMasterNameCh>Smith, Mike A.</RscMasterNameCh>
<InstitutionAbrvCh>SPL</InstitutionAbrvCh>
<AgencyAbrvCh>SPFD</AgencyAbrvCh>
<RegionAbrvCh>OPS</RegionAbrvCh>
<StationAbrvCh>B19</StationAbrvCh>
<PUnitAbrvCh>BAT19</PUnitAbrvCh>
<PosJobAbrvCh>BC-S</PosJobAbrvCh>
</Record>
<Record>
<RscPayrollIDCh>12345</RscPayrollIDCh>
<RscEmployeeIDCh>12345</RscEmployeeIDCh>
<RscMasterNameCh>Smith, John A.</RscMasterNameCh>
<InstitutionAbrvCh>SPL</InstitutionAbrvCh>
<AgencyAbrvCh>SPFD</AgencyAbrvCh>
<RegionAbrvCh>OPS</RegionAbrvCh>
<StationAbrvCh>S15</StationAbrvCh>
<PUnitAbrvCh>E15</PUnitAbrvCh>
<PosJobAbrvCh>CAPT</PosJobAbrvCh>
</Record>
<Record>
<RscPayrollIDCh>123456</RscPayrollIDCh>
<RscEmployeeIDCh>123456</RscEmployeeIDCh>
<RscMasterNameCh>Smith, Bob R.</RscMasterNameCh>
<InstitutionAbrvCh>SPL</InstitutionAbrvCh>
<AgencyAbrvCh>SPFD</AgencyAbrvCh>
<RegionAbrvCh>OPS</RegionAbrvCh>
<StationAbrvCh>S15</StationAbrvCh>
<PUnitAbrvCh>E15</PUnitAbrvCh>
<PosJobAbrvCh>ENG</PosJobAbrvCh>
</Record>
</Records>
</Data>
I would like to format the XML so that it looks something like this:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Data>
<Date>2019-05-07-07:00</Date>
<Headers></Headers>
<Records>
<Record>
<StationAbrvCh>B19</StationAbrvCh>
<RscMasterNameCh>Smith, Mike A.</RscMasterNameCh>
</Record>
<Record>
<StationAbrvCh>S15</StationAbrvCh>
<RscMasterNameCh>Smith, John A.</RscMasterNameCh>
<RscMasterNameCh>Smith, Bob R.</RscMasterNameCh>
</Record>
</Records>
I would like my roster to list each crew member under the Station they are assigned to for the day.

Answer 1

If you are using XSLT 1.0, Muenchian grouping is the best approach to achieve it as below:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes" />
<xsl:key name="groups" match="/Data/Records/Record" use="StationAbrvCh" />
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()" />
</xsl:copy>
</xsl:template>
<xsl:template match="/Data/Records">
<xsl:copy>
<xsl:for-each select="Record[generate-id() = generate-id(key('groups', StationAbrvCh)[1])]">
<xsl:copy>
<StationAbrvCh><xsl:value-of select="StationAbrvCh" /></StationAbrvCh>
<xsl:for-each select="key('groups', StationAbrvCh)">
<RscMasterNameCh><xsl:value-of select="RscMasterNameCh" /></RscMasterNameCh>
</xsl:for-each>
</xsl:copy>
</xsl:for-each>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
See demo here: https://xsltfiddle.liberty-development.net/pPzifpM

Answer 2

Using XSLT 2.0 it is quite easy.
In the template maching Records, you should use for-each-group
selecting Record elements and grouping them by StationAbrvCh.
Within each group you should:
Generate StationAbrvCh element, filled with the current grouping key
(also StationAbrvCh).
Run a for-each loop for the current group, copying to the output the
current RscMasterNameCh.
The script should contain also the identity template.
Below you have an example script:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes"/>
<xsl:template match="Records">
<xsl:copy>
<xsl:for-each-group select="Record" group-by="StationAbrvCh">
<xsl:copy>
<StationAbrvCh><xsl:value-of select="current-grouping-key()"/></StationAbrvCh>
<xsl:for-each select="current-group()">
<xsl:sequence select="RscMasterNameCh"/>
</xsl:for-each>
</xsl:copy>
</xsl:for-each-group>
</xsl:copy>
</xsl:template>
<xsl:template match="#*|node()">
<xsl:copy><xsl:apply-templates select="#*|node()"/></xsl:copy>
</xsl:template>
</xsl:stylesheet>
Maybe, to fully understand each detail of the above solution,
you should search the Web for description of for-each-group
and related functions (current-grouping-key() and current-group).