This markup creates a numbered example that includes a cross-reference to the third line.
<ex number> Enter Daily Account Total Run Invoice Summary Report Go to Monthly Ledger <lineno id=ledger> Run Daily Update <\ex> . . . To run closing reports, return to <xref ledger> and run the Past Due Accounts Report.
The line number where the ID is located is substituted for the <xref ledger> cross-reference. It produces this sentence:
To run closing reports, return to 3 and run the Past Due Accounts Report.
The end tag is not required for <lineno>.