BOX: Wrap text or in the box, in additional, customize the area with a background
BGIMG: Background img for page or post. Options are repeat, repeat-x, repeat-y, fixed.
SZIMG: customize width and height for an img
Hover: css hover code
Justify: Justify the text in the area.
Clear: css clear code
Float: Float text right or left.
Background Color: Customize background color for a text, or object.
Background Color 2: Customize background, height and width for text, or object.
Limit: Limit the size of the area (in pixel)
LimitR: Limit the size of the area (in pixel), then float it right
Margin: Append margin (in pixel) to the text or object.
Height: Specify the height of object (in pixel)
This is mostly only supported in ASFv1 but some of the elements are still being supported in ASFv2.
I've reconstructed an old sample post:
https://www.anime-sharing.com/threads/checkmates-bbcode-workshop.282626/#post-6982257