Dell XPS 18 (1810, Early 2013) - Manual (Page 43)

Locating Your Service Tag and
Express Service Code
You need your computer’s Service Tag/Express Service Code when
you contact Dell regarding your computer. The Express Service Code
helps the automated telephone support system redirect your call to the
appropriate support department.
The Service Tag and Express Service Code for your computer are
located on a label at the back of your computer.
CAUTION: Lay your computer face down before you look for Service Tag
and Express Service Code.
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