Vincent
The form is misleading, the legal test is whether you can walk 20m or less, if you cannot reliably walk more than 20m (e.g. 20m or less) on the majority of days then you should tick the "no more than 20m box.
The reason the numbering is different is because the form has two extra question at the beginning.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems