As I had 'planned' it, there would not be confusion between the several columns and the unit of weight.
The measurements are attributes of the packet size. but across the range they can be sizes of vloume, height x width, cubic or length. whatever type, the unit would be consistent per record since we wouldn't be having 24cm x 3 inches x 5 feet.
Your hint seems to steer me towards this place
create table package sizes
( id int not null auto_increment primary key
, container size
, unit of measurement
| 1 | glass jar A | 50 | ml |
| 2 | packet | 24 x 12 x 6 | cm |
But what if I want to search through package sizes, to determine which is most suitable for the postage costs?