Its about File Sorting
C:\sorttest>dir /on /b
X12.TXT
X13.TXT
X1A.TXT
X1B.TXT
XAB.TXT
Shows in this order (when sorted by name) in explorer:
X1A.TXT
X1B.TXT
X12.TXT
X13.TXT
XAB.TXT
Read what Michael Kaplan has to say about it ... Very interesting read.