What Excel is
An Excel workbook is a zip archive of XML parts describing sheets, cells, formulas, styles and charts. The .xlsx extension is that format; .xls is the older binary one from before 2007.
Finance, operations and anyone who received a file from finance or operations.
What reStructuredText is
reStructuredText simple tables underline the header with equals signs and align columns with spaces.
Python documentation, Sphinx projects and anything on Read the Docs.
What changes when you convert Excel to reStructuredText
Only the first sheet is read, and cells are read as the text Excel displays rather than the number underneath. That matters for dates: a cell showing 15/03/2026 arrives as that string, not as a serial number you would then have to decode.
The equals-sign rule under the header is what tells Sphinx the first row is a header. Without it the table renders as data with no heading.
What carries over from Excel to reStructuredText
Excel records 3 things about a table that reStructuredText has no way to hold.
Excel distinguishes a number from the text of a number; reStructuredText does not, so every value arrives as text and has to be re-parsed by whatever reads it next.
An empty cell and a missing one are the same thing in reStructuredText, so a null and an empty string in the Excel both come out blank and can no longer be told apart.
reStructuredText marks its header cells differently from its data cells, so the first row is written with that marker.
Anything visual in the Excel - weight, alignment, colour, column widths - has no counterpart in reStructuredText and is dropped. The values are what survives.