XSLT copy-of doesn't match document - xslt

Question

I'm receiving a large XML with many documents and I need to break it down to single documents for processing. I'm using XSLT. In the source /ACC_DOCUMENT04/IDOC is a recurring element, but in each result of the transform it would a singular.
I'm using XSLT 1.0 with an input parameter, and I've done similar ones before, but I cannot figure out why my transform doesn't find any data at all. This is my latest attempt: https://xsltfiddle.liberty-development.net/eixh2wH
Input XML:
<?xml version="1.0" encoding="UTF-8"?>
<ACC_DOCUMENT04>
<IDOC BEGIN="1">
<EDI_DC40 SEGMENT="1">
<TABNAM>EDI_DC40</TABNAM>
<DIRECT>2</DIRECT>
<IDOCTYP>ACC_DOCUMENT04</IDOCTYP>
<MESTYP>ACC_DOCUMENT</MESTYP>
<MESFCT/>
<SNDPOR>SAPXQ1</SNDPOR>
<SNDPRT>LS</SNDPRT>
<SNDPRN>MAGENTO</SNDPRN>
<RCVPOR>SAPEQ1</RCVPOR>
<RCVPRT>LS</RCVPRT>
<RCVPRN>EQ1CLNT400</RCVPRN>
</EDI_DC40>
<E1BPACHE09 SEGMENT="1">
<OBJ_TYPE>BKPFF</OBJ_TYPE>
<OBJ_KEY>FB01</OBJ_KEY>
<BUS_ACT>RFBU</BUS_ACT>
<USERNAME>SAPPI</USERNAME>
<HEADER_TXT>SL000000601</HEADER_TXT>
<COMP_CODE>1713</COMP_CODE>
<DOC_DATE>20220701</DOC_DATE>
<PSTNG_DATE>20220701</PSTNG_DATE>
<TRANS_DATE>20220701</TRANS_DATE>
<FISC_YEAR>2022</FISC_YEAR>
<DOC_TYPE>ZM</DOC_TYPE>
<REF_DOC_NO>SL000001861</REF_DOC_NO>
</E1BPACHE09>
<E1BPACGL09 SEGMENT="1">
<ITEMNO_ACC>1</ITEMNO_ACC>
<GL_ACCOUNT>0012100050</GL_ACCOUNT>
<ITEM_TEXT>NK9HZT53LLBX8N82</ITEM_TEXT>
<REF_KEY_1>MC</REF_KEY_1>
<VALUE_DATE>20220701</VALUE_DATE>
<ALLOC_NMBR>SL000001861</ALLOC_NMBR>
</E1BPACGL09>
<E1BPACAR09 SEGMENT="1">
<ITEMNO_ACC>2</ITEMNO_ACC>
<CUSTOMER>0001077997</CUSTOMER>
<PAYMT_REF>SL000001861</PAYMT_REF>
<ALLOC_NMBR>SL000001861</ALLOC_NMBR>
<ITEM_TEXT>NK9HZT53LLBX8N82</ITEM_TEXT>
</E1BPACAR09>
<E1BPACCR09 SEGMENT="1">
<ITEMNO_ACC>1</ITEMNO_ACC>
<CURRENCY>USD</CURRENCY>
<AMT_DOCCUR>14.65</AMT_DOCCUR>
</E1BPACCR09>
<E1BPACCR09 SEGMENT="1">
<ITEMNO_ACC>2</ITEMNO_ACC>
<CURRENCY>USD</CURRENCY>
<AMT_DOCCUR>-14.65</AMT_DOCCUR>
</E1BPACCR09>
</IDOC>
<IDOC BEGIN="2">
<EDI_DC40 SEGMENT="2">
<TABNAM>EDI_2</TABNAM>
<DIRECT>2</DIRECT>
<IDOCTYP>ACC_DOCUMENT04</IDOCTYP>
<MESTYP>ACC_DOCUMENT</MESTYP>
<MESFCT/>
<SNDPOR>SAPXQ1</SNDPOR>
<SNDPRT>LS</SNDPRT>
<SNDPRN>MAGENTO</SNDPRN>
<RCVPOR>SAPEQ1</RCVPOR>
<RCVPRT>LS</RCVPRT>
<RCVPRN>EQ1CLNT400</RCVPRN>
</EDI_DC40>
<E1BPACHE09 SEGMENT="1">
<OBJ_TYPE>BKPFF</OBJ_TYPE>
<OBJ_KEY>FB01</OBJ_KEY>
<BUS_ACT>RFBU</BUS_ACT>
<USERNAME>SAPPI</USERNAME>
<HEADER_TXT>SL000000598</HEADER_TXT>
<COMP_CODE>1713</COMP_CODE>
<DOC_DATE>20220701</DOC_DATE>
<PSTNG_DATE>20220701</PSTNG_DATE>
<TRANS_DATE>20220701</TRANS_DATE>
<FISC_YEAR>2022</FISC_YEAR>
<DOC_TYPE>ZM</DOC_TYPE>
<REF_DOC_NO>SL000001864</REF_DOC_NO>
</E1BPACHE09>
<E1BPACGL09 SEGMENT="1">
<ITEMNO_ACC>1</ITEMNO_ACC>
<GL_ACCOUNT>0012100050</GL_ACCOUNT>
<ITEM_TEXT>W82RKHDLHRWZNN82</ITEM_TEXT>
<REF_KEY_1>MC</REF_KEY_1>
<VALUE_DATE>20220701</VALUE_DATE>
<ALLOC_NMBR>SL000001864</ALLOC_NMBR>
</E1BPACGL09>
<E1BPACAR09 SEGMENT="1">
<ITEMNO_ACC>2</ITEMNO_ACC>
<CUSTOMER>0001077997</CUSTOMER>
<PAYMT_REF>SL000001864</PAYMT_REF>
<ALLOC_NMBR>SL000001864</ALLOC_NMBR>
<ITEM_TEXT>W82RKHDLHRWZNN82</ITEM_TEXT>
</E1BPACAR09>
<E1BPACCR09 SEGMENT="1">
<ITEMNO_ACC>1</ITEMNO_ACC>
<CURRENCY>USD</CURRENCY>
<AMT_DOCCUR>56.21</AMT_DOCCUR>
</E1BPACCR09>
<E1BPACCR09 SEGMENT="1">
<ITEMNO_ACC>2</ITEMNO_ACC>
<CURRENCY>USD</CURRENCY>
<AMT_DOCCUR>-56.21</AMT_DOCCUR>
</E1BPACCR09>
</IDOC>
</ACC_DOCUMENT04>
Transform:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:param name="Doc" select="SL000000598" />
<xsl:template match="/ACC_DOCUMENT04">
<ACC_DOCUMENT04>
<xsl:copy-of select="./IDOC[E1BPACHE09/HEADER_TXT=$Doc]"/>
</ACC_DOCUMENT04>
</xsl:template>
</xsl:stylesheet>
The expected output would be just the second IDOC, so abbreviated:
<?xml version="1.0" encoding="UTF-8"?>
<ACC_DOCUMENT04>
<IDOC BEGIN="2">
...
<E1BPACHE09 SEGMENT="1">
...
<HEADER_TXT>SL000000598</HEADER_TXT>
<REF_DOC_NO>SL000001864</REF_DOC_NO>
...
</E1BPACHE09>
...
</IDOC>
</ACC_DOCUMENT04>

Answer 1

Change:
<xsl:param name="Doc" select="SL000000598" />
to:
<xsl:param name="Doc" select="'SL000000598'" />
or:
<xsl:param name="Doc">SL000000598"</xsl:param>
What you have now is looking for a root element named SL000000598.
Note that there should be no problem if you leave it as it is - or change it to <xsl:param name="Doc"/> - and pass the value as the parameter at runtime. It's only your hard-coded test that fails.