They may appear in any order. Attribute names are always case-insensitive.
Attribute values are generally case-insensitive.
This attribute indicates the number of columns the contained data will be split into. The browser should try to evenly distribute the content evenly across each of the columns in order to achieve roughly the same column height. Positive integers - default is 1. Specified as positive integers with the default being 10. However, through direct experimentation, this attribute seems to control the total width of the column apparatus, not the width of each individual column.