A code number with no suffix identifies a flat shape. * But see Note 1.

Note 1:  Where the standard part is domed, the suffix is omitted. This will be shown in the shape description.
Shapes such as butterflies & dragonflies come with unpierced, '/p' or '/pp' options.
'/p, '/pp' only appear when both pierced and unpierced versions of a shape are available (e.g. 724/22, 724/22/p).

Shapes such as crosses are only available pierced (e.g. 901/20), while some dedicated necklace shapes are only available pierced twice (e.g. 458/20).
Here, '/pp' does not appear.

We recommend the heavier metal gauge for shapes with thin parts like dragonflies or crosses, flat shapes larger than 50 mm (2 in) or domed shapes larger than 55 mm (2.5 in).
The thicker guage is preferable if you do not intend to counter enamel the piece (that is, enamelled back and front to balance out metal stresses).
In general domed shapes suffer less from heat distortions than flat shapes.

Ovals, discs and rectangles are supplied flat and unpierced unless a '/p', '/d' or '/pp' follows the code number.

A code number with suffix '/d' identifies a domed shape.

And '/dd' is a deeply domed shape.

A code number with suffix '/p' identifies a pierced shape.(e.g. 502/20/p).
The pierce hole diameter for most shapes is 1.9 mm.
A few of the smaller shapes have 1.5mm pierce holes, and for suitable shapes a 3mm hole is available for use with thongs ('/p/3mm').

A '/pp' means the shape is pierced twice for use as a necklace component (e.g. 469/20/pp).

A lugged shape has a '/l' suffix (e.g. 815/20/l).
If the standard shape is lugged, the '/l' suffix means the shape has two lugs.