I’m having a hard time understanding what “value” is?
value is an attribute, like id or type
the value attribute is important to label well the data from the form
following the example for the radio buttons, if your two radio buttons have value one of indoor the other of outdoor, the data of the form will have indoor-outdoor=indoor or indoor-outdoor=outdoor, so it’s understandable what button is checked.
you set the attribute value as any other attribute attributeName=attributeValue