What is "data type" in layer definition of PDK document

When I read the PDK document, there is a column defining "data type" of layer. Its value can be "0" or an other number.
My question is what does "data type" mean.

Thank you in advanced.

Each layer in GDSII format is defined by two integers:

1. Layer number

2. Layer datatype.

Combination of these two integers uniquely defines a layer.

Often, different layers will have different layer numbers and zero datatype.
Also often, different things belonging to the same layer would be described by layers with the same number but different datatypes - like shapes, pins, etc.

timof said:

Each layer in GDSII format is defined by two integers:

1. Layer number

2. Layer datatype.

Combination of these two integers uniquely defines a layer.

Often, different layers will have different layer numbers and zero datatype.
Also often, different things belonging to the same layer would be described by layers with the same number but different datatypes - like shapes, pins, etc.

Click to expand...

Thank you for your kind reply. I have looked back to the PDK matterial. It's seem that "datatype = 0" is for drawing purpose. Others will be defined by the manufacturer for dummy, text, pin, slot... as you said.

Use of datatypes is pretty variable. I've seen schemes where
there were "circuit" and "manufacturing" mask shop processing,
like 13/0 for metal1/drawing circuit use, and 13/1 for foundry
metal like CD bars and alignment marks (circuit metal is sized
for WYSIWYG outcomes, foundry metal is printed as-drawn so
there's no fudging in the inline control structures that get your
flow to the WYSIWYG outcome).

And I see one currently where the isolation mask has half a
dozen datatypes, used as "feedstock" for creating N and P
buried layers, N and P back and front collector by booleans
(they do not draw the collector features; kooky).

Basically any backwater foundry made up their own CAD setup
"back in the day" and you never know what to expect. Maybe
things have tightened up in the modern foundries and the couple
of remaining mask shops and the increasingly homogenous (by
dint of few survivors) CAD tools space.

It's free bits; expect them to be used opportunistically and
idiosyncratically.