The regular expression:

(?-imsx:[a-zA-Z][a-zA-Z][a-zA-Z]\d\d,\s+interlock)

matches as follows:
  
NODE                     EXPLANATION
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(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  [a-zA-Z]                 any character of: 'a' to 'z', 'A' to 'Z'
----------------------------------------------------------------------
  [a-zA-Z]                 any character of: 'a' to 'z', 'A' to 'Z'
----------------------------------------------------------------------
  [a-zA-Z]                 any character of: 'a' to 'z', 'A' to 'Z'
----------------------------------------------------------------------
  \d                       digits (0-9)
----------------------------------------------------------------------
  \d                       digits (0-9)
----------------------------------------------------------------------
  ,                        ','
----------------------------------------------------------------------
  \s+                      whitespace (\n, \r, \t, \f, and " ") (1 or
                           more times (matching the most amount
                           possible))
----------------------------------------------------------------------
  interlock                'interlock'
----------------------------------------------------------------------
)                        end of grouping
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