Most of the smartness of Visio comes from the power of the ShapeSheet. Every shape in Visio, even if it is just text, has a ShapeSheet that most users do not see. In fact, a lot of users do not realise that there is a Developer ribbon tab that is not visible by default.

It can be made visible by ticking it in the Developer tab in the Visio Options / Customize Ribbon dialog. This can be opened from File / Options, or by using the Customize the Ribbon… right-mouse menu option in a blank area of the ribbon.

The Show ShapeSheet drop-down button in the Developer ribbon tab will open the ShapeSheet of the selected shape, active page or active document.
The ShapeSheet is divided into Sections, Rows and Cells. Some of the Sections always exist in a shape of a particular type (this also includes pages and documents), whilst others are optional. The rows in some of these optional sections can be renamed for clarity, if required. For example, the default name for the first row in the User-defined Cells section is Row_1, but it can be renamed, just like ShapeAppearance in the following image of the ShapeSheet of an Off-page reference shape from the Basic Flowchart Shapes stencil.

Notice that the ShapeSheet can display either the Formulas or the Values, and that not all of the Sections need to be visible, and individual sections can be expanded or collapsed. The ShapeSheet contains many sections, so it is usually necessary to scroll.
Each of the cells can be referenced by name within formulas in other cells. They can also be referenced by their Section, Row, Cell indices in code using the CellsSRC[…] property. However, this reference is all about formulas using the functions available in the ShapeSheet. There are currently 210 functions listed in the Microsoft Docs, but some of them do not have an example, or they are difficult to follow without a visual the examples. Most of the functions work perfectly within Visio for the Web, just as they do in Visio for the Desktop. There are some exceptions to this, and one in particular, CALLTHIS(), is unlikely to ever work in the web because it is used to run code within a Visual Basic project.
Over the next few months, each of the functions will be described more visually, and there will be similarity in the way that each page in the document demonstrates the function.

The border is a Visio container shape and contains a hyperlink to the Microsoft Docs for the specified function, and the ScreenTip is displayed in the associated Word Box callout.
The mauve circles are Off-page reference shapes that provide hyperlinks to specific pages within the Visio document.
The text of the coloured rectangle is evaluated as a Visio ShapeSheet formula by the associated Price Tag callout (using the EVALTEXT() function).
A second callout sometimes suggests how the target shape can be edited to demonstrate the ShapeSheet function. And another callout may display the value in another cell, such as the Angle in the following example,
There may be other shapes, such as the green part-filled circle above, that may further demonstrate the output of the function.
Most of these callout shapes make use of the CALLOUTREFTARGET() function. This is another example of the Structured Diagram concept in Visio, eg Containers, Lists, Callouts and Connectors.
Although the documents are viewable from my OneDriveForBusiness folder, they will need to be downloaded and placed into your ODfB or SharePoint tenant for them to be editable in the web.
You may get a warning dialog when switching from one page to another in the web, but it can be safely refreshed.
The articles will appear in the list and grid below, along with other related topics, so subscribe, or keep a look out for new ones.
Viewing Visio Document Changes in Git
Developing a Visio solution usually involves both .Net code and Visio ShapeSheet formulas. Good practice dictates that the source code is saved into a code repository, such as Git, where changes can be committed and commented. Visual Studio 2019 now includes native Git support, and can be linked to Azure DevOps easily. The code can…
Visio ShapeSheet Functions D-F
The second 32 of the Visio ShapeSheet functions that start with the letters D through to F are visually described in the Visio document below that is available for download. Please see the general introduction to this series at ShapeSheet Functions A-Z for more information. Each of the ShapeSheet functions that start with the letters…
Visio ShapeSheet Functions A-C
The first 36 of the Visio ShapeSheet functions that start with the letters A through to C are visually described in the Visio document below that is available for download. Please see the general introduction to this series at ShapeSheet Functions A-Z for more information. Each of the ShapeSheet functions that start with the letters…
Using the CALLTHIS function in Visio
Visio was the first non-Microsoft application to include VBA within it back in the mid-nineties. All of the desktop Microsoft Office applications currently include VBA, although Microsoft have been rumoured to want to replace it for many years, and now there is an alternative scripting option becoming available that is suitable for the web too.…
Referencing Visio Shapes
Every Visio shape must have a unique name in the collection that it belongs to, and to ensure this, Visio automatically one using the master name or just “Sheet”, if not an instance of a master, followed by a period (“.”) and the ID. However, a user can rename a shape, and Visio will then…
Play Backgammon with Visio
Still in lockdown on holiday, so I thought I would create a version of backgammon that can be played with Visio for the web. This was inspired by my original Visio tutor, the late David Edson, who created a Visio backgammon document which included macros. Macros are not available in Visio for the web, so…