Consider the following call numbers: L19.M322; LA23.M38; LA2340.M371; LA2340.M38. These would appear in the following order on the shelf:

1) L19. M322
*Explanation: Call numbers starting with "L" come befor "LA" call numbers

2) LA23. M38
*Explanation: 23 comes before 2340. 

3) LA2340. M371
*Explanation: When read like a decimal, .371 comes before .38

4) LA2340. M38