Proposal of a excel workbook using a readable YAML text file structure

excel-workbook.yaml

%YAML 1.2
%TAG !excel! tag:microsoft.com,2019:excel/
%TAG !w3c! tag:w3.org,2000:

--- !excel!workbook

Metadata:
  Authors: Leonardo Machado Carreiro
  Last saved by: Leonardo Machado Carreiro
  Program name: Microsoft Excel

Sheets:
  - Name: Sheet1
    Visible: Yes
  - Name: Sheet2
    Visible: Yes
  - Name: Sheet3
    Visible: No

--- !excel!sheet

For: Sheet1
Content: !excel!sheet-content |
  | A | B  | C                    | D           |
  +---+----+----------------------+-------------+
  | 1 |  2 |                      |             |
  | 3 | 40 |                      |             |
  |   |    |/=LONG.FORMULA.TO.SHO |             |
  |   |    | W.A.SINGLE.ROW.SERIA |             |
  |   |    | LIZED.IN.MULTIPLE.LI |             |
  |   |    | NES()               /|             |
  |[    1 ]|                      | =SUM(A1:B2) |
Metadata:
  Columns:
    C:
      Break size: 20

# All cells have a padding of 1 white-space, that can be replace for
# control chars like for /multiple-lines-row/ or [merge-cells]

# C3 is a single cell with a long formula: use of '/' on the top-left
# and bottom-right padding of the cell

# A4:B4 is a merged cell: use of '[' and ']' on the top-left and
# bottom-right padding of the cell

# It must have a way to set a fixed break-size, so the changes in one
# cell won't have to change all the lines in the table to keep the content
# horizontally align, resulting in dirty diffs in revision history

--- !excel!sheet

For: Sheet2
Content: !excel!sheet-content |
  | A |
  +---+
  |   |

--- !excel!sheet

For: Sheet3
Content: !excel!sheet-content |
  | A |
  +---+
  |   |

--- !excel!sheet-style

For: Sheet1
Style ids: !excel!sheet-style-content |
  | A | B |
  +---+---+
  |   |   |
  |   | 1 |

--- !excel!styles

- Id: 1
  Styles: !w3c!css
    font-weight: bold
    color: !w3c!color 0xFF0000

--- !excel!workbook-files

img-1.gif: !!binary |
  R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5
  OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+
  +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC
  AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs=

img-2.gif: !!binary R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/++f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLCAgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs=