What you can do with each format

The table is built from the format registry inside the core: it’s not a promise in words, but what the core reports about itself. Here you can see how one format differs from another, even before the pilot.

Full — works with no caveats. Partial — works within declared bounds; the rest is rejected with a reason. In the “Save” column: to the same file — writes back to the source format; export only — you can save, but only to a different file; the source format isn’t written back; not possible — there’s no saving at all; a workbook from such a file has to be exported to a different format.

Precision answers the question “partial — relative to what?”: the core states which reference model it treats this format by. The benchmark is benchmark, meaning XLSX; the other classes are described relative to it. The package carries over whole — whatever the core doesn’t parse in the file, it doesn’t touch either: the unparsed parts go back exactly as they were. Like a template — the file opens and edits like a workbook, but stays a template, so edits leave through export to a regular file, and the template itself is never rewritten. Binary compatibility, XML compatibility, and the ODF family — their own storage method, which doesn’t match XLSX; exactly what the core gives up for these formats is stated in the contract column of the same row. Delimited text — the format holds a single grid of values: there’s simply no room in it for a second sheet, formulas, or formatting.

FODS — flat ODS: the same OpenDocument format, but as a single XML file instead of a zip package. For documents, its counterpart is XODT.

Format	Precision	Open	Edit	Save	How it saves	What’s written into the contract
XLSX	benchmark	full	full	to the same file	native format both ways	macros aren’t executed, VBA isn’t interpreted, there’s no shared M-language runtime, and Power Query isn’t a full match
XLSM	package carries over whole	full	partial	to the same file	native format, unparsed parts carry over as-is	macros aren’t executed, VBA isn’t interpreted, there’s no shared M-language runtime, and Power Query isn’t a full match
XLSB	binary compatibility	full	partial	to the same file	native format both ways	—
XLTX	like a template	full	partial	export only	native format both ways	macros aren’t executed, VBA isn’t interpreted, there’s no shared M-language runtime, and Power Query isn’t a full match
XLTM	like a template	full	partial	export only	native format, unparsed parts carry over as-is	macros aren’t executed, VBA isn’t interpreted, there’s no shared M-language runtime, and Power Query isn’t a full match
XLS	binary compatibility	full	partial	export only	export to a canonical form	macros aren’t executed, VBA isn’t interpreted, there’s no saving back to the same format, and styles aren’t a full match
ODS	ODF family	full	partial	to the same file	native format both ways	styles aren’t a full match
FODS	ODF family	full	partial	partial	native format both ways	no saving to the same format, styles don’t match completely
SpreadsheetML 2003	XML compatibility	full	partial	export only	export to a canonical form	no saving back to the same format
CSV	delimited text	partial	partial	to the same file	native format both ways	the format holds a single sheet
TSV	delimited text	partial	partial	to the same file	native format both ways	the format holds a single sheet
TXT	delimited text	partial	partial	to the same file	native format both ways	the format holds a single sheet
HTML	delimited text	partial	partial	not possible	—	the format holds a single sheet

How to use this

The “What is written into the contract” row isn’t fine print but part of the agreement: the core declares these limits itself, and you can refer to them during acceptance.

The “macros are not executed” and “VBA is not interpreted” items for XLSM and XLTM are the default declaration: until a build is released with VBA execution enabled (a vendor switch), the contract answers about the format exactly this way. Running a macro is already in the contract — on a copy of the workbook, with a preview of the changed cells, commit, and rollback (how macro execution works). For XLSX, XLTX and XLS these items are always present: these formats never contain macros.