Windows has certain naming restrictions which can be found here: https://support.microsoft.com/en-us/help/909264/naming-conventions-in-active-directory-for-computers-domains-sites-and
 
It is important to note that on the Components | Naming Methods screen, you will find a "Validation" regular expression.

The regular expression by default only accepts valid Windows naming conventions.

If you would like to test your naming convention, you can test that here:
https://www.regular-expressions.info/javascriptexample.html
by placing in the regular expression listed above and testing to see if you get a successful match or not.

The "Subject String" should be where you put the computer name you are testing:
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smartImager has nothing to do with naming the computer as it merely passes the string to Windows.  It does however check the name against the regular expression first to see if it is valid or not.  You can change the validation regular expression if you would like to put additional restrictions on your naming method.