rpm question

From: Double Dumbass on You (spam_me_gently_with_a_chainsaw_at_yahoo.com)
Date: 08/05/04

Date: Thu, 5 Aug 2004 14:08:26 -0700

When you get the file mode information from rpm -q --dump, there are 7
digits. The last three represent the rwx status, i.e. the numeric
representation. What are the first 4 digits?

0100755 = -rwxr-xr-x
0100777 = -rwxrwxrwx

What is the 0100??