HScroll may only be set when the object is created with ⎕WC and may not subsequently be changed with ⎕WS or assignment.

When applied to a Combo, or to an Edit object with Style 'Single' (that is, a single-line edit field), the value 0 inhibits scrolling, and prevents the user from entering more data when the field is full. If instead it has the value ¯2, the field is scrollable, and the length of data that may be entered is not limited by the length of the field.

When applied to an Edit object with Style 'Multi' (that is, a multi-line text box), the value 0 inhibits scrolling, and causes individual lines to be "word-wrapped". The values ¯2 and ¯1 enable sideways scrolling, and permit individual lines to exceed the width of the object. The value ¯1 means that a horizontal scrollbar is provided.

For a Scroll object, the scrollbar is horizontal if HScroll is ¯1 and vertical if HScroll is 0. For a Form, a horizontal scrollbar is provided if HScroll is set to ¯1. The default value is 0 (no scrollbar).

For a StatusBar, TabBar or ToolBar with Align set to Top or Bottom, HScroll determines whether or not a horizontal scrollbar is provided and how the object positions its children. If HScroll is 0 (the default) the object organises its children in multiple rows and does not provide a scrollbar. If HScroll is ¯1 or ¯2, the object organises its children in a single row and provides a mini scrollbar to allow those positioned beyond the right edge of the object to be scrolled into view. If HScroll is ¯1, the scrollbar is always shown. If HScroll is ¯2, it is only shown when needed.

For a Grid, HScroll may be 0 (no horizontal scrollbar), ¯1 (scrollbar is displayed when required), ¯2 (same as ¯1) or ¯3 (scrollbar is always displayed).