Choices and choice columns

What it does

A choice column offers a fixed set of options, rendered as a drop-down. The option set can be defined inside the column (local) or shared across the environment (global), and the column can be single-select (Choice) or multi-select (Choices).

Key facts

Global choices are the default when you create a new choice in the modern designer. Getting a local choice means selecting View more and picking Local choice explicitly.
Each option stores an integer value, not the label. The label is display metadata; the integer is what's in the database and what integrations see.
Multi-select choices don't work with workflows, business process flows, actions, dialogs, business rules, charts, rollup columns or calculated columns. They're also out for reports, and for SLAs and routing rules where those exist.
Multi-select columns can't be enabled for sorting.
Removing an option that's already in use leaves the affected rows holding an invalid value. Microsoft's guidance is to migrate the data to a valid option before you delete anything.
Global choices can also arrive through solution import or be created programmatically, so the list in an environment isn't only what makers built in the UI.
Column mapping between tables in a 1:N relationship needs the option sets to line up, which is the practical argument for going global on anything shared.

When to use / skip

Go global when the same list genuinely appears on more than one column — status categories, regions, product families — because maintaining two copies that drift apart causes real errors, particularly with column mapping. Go local when you know the list belongs to exactly one column, because an environment with four hundred global choices is its own kind of unmaintainable. Reach for multi-select sparingly: the moment someone wants to report on it, drive a business rule from it, or roll it up, you'll be rebuilding it as a related table.

Configuration decisions

Global versus local per choice, decided on genuine reuse rather than a vague sense that it might be reused later.
Whether the concept is really a choice at all, or a lookup to a small reference table that business users can maintain themselves.
Integer values — whether you let the platform assign them or set deliberate, documented values that integrations can rely on.
Whether multi-select is worth losing business rules, rollups, charts and workflow support.
Who owns the list and how new options get added after go-live, since every addition is a solution change.

Gotchas

Renaming an option label changes what users see but nothing underneath. Every filter, view, integration mapping and piece of code still keys off the integer, so a rename that looks harmless can quietly make a report meaningless.
Deleting an option is worse. Rows keep the orphaned integer and render blank or odd, and there's no warning listing what's affected.
Global choices accumulate. Makers accept the default, and eighteen months later there's a global choice for every column in the system with no way to tell which are shared.
Multi-select values come out of the Web API as a comma-separated list of integers. Anyone building an integration against them needs to be told before they design the mapping, not after.
A local choice can't be promoted to global in place. You create a global one and repoint the column, which means a data migration.

Consultant notes

Set the rule at kickoff: local by default, global only with a named second consumer. It's the cheapest governance decision on the project.
Tell the client plainly that choice values are effectively permanent. Adding options is easy, changing or removing them is a data migration, and they should treat the list as part of the design not a screen setting.
If the client wants business users to manage the list themselves, that's a reference table with a lookup, not a choice. Choices need a maker and a deployment.
Document the integer values for anything an integration touches, and version that document. It's the thing you'll be asked for during the first support incident.

Worth revisiting if option label and value management ever gets a proper impact-analysis tool in the maker portal.