there is the concepts of "drawn length" vs. "effective length" vs. "physical length"

What you draw (in Layout) is not what you see (electron microscope) vs. what it performs like in comparison to models ( effective length)

Most foundries have largely tossed this out of the conversation and links everything to the "drawn length"

You say in your schematic, that L=90nm, W=400nm and everything links and simulates from there.

Under an electron microscope the L = 69 and the W= 395 but you really don't care because the transistor model is tied to the drawn length, and simulations vs. silicon are in agreement.

With things like angualr implants (aka halo implants) it starts to get a little fuzzy when you realize that you would need to account for the angles and depth issues as well.

(substitute the word "width" for "length" in the above, as well)

not a problem, happy to help,
Jerry