Chapter 7: title was adjusted for consistency with remaining chapters

Extraneous punctuation was removed; where missing or unprinted, expected punctuation was added. Misspelled words were corrected. Line spacing was adjusted to context. In Chapter 13 and Appendix D, some illustrations were moved to be closer to the text that references them.

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The following were changed:

Changed ‘deleted’ to ‘detected’ in Table 2-2.
Added word ‘a’ to ‘columns to pass a given point’ in Section 3001.
Changed ‘PI’ to ‘PL’ in Figure 11-3.
Deleted word ‘a’ from 'advantages of a motorized urban patrols’ in