Permanent help key for values for & will be ignored at runtime

What causes this issue?

You are editing an element of a table control and want to assign the
value
2 - permanent input help key
to the "input help key" attribute.

System Response

This attribute value will be ignored at runtime.
To prevent following columns always being obscured by the input help
key, the system assigns the value
empty - temporary input help at cursor position, if possible
instead.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.