What does I1, I2, U1 mean in a Visio database relationship diagram?

Question

I am doing reverse engineering a database to create an ER database diagram in Visio. When I show the table in Visio, on the left side of the entity diagram, I see characters next to the column names, which I don’t know what they mean. Symbols such as U1, U2, l1, l2, l5 ... etc. Other characters like PK (primary key) and FK (foreign key) also appear in the same area, but this obviously makes sense to me.

Answer 1

These are other types of indexes.

U1 = unique index 1 ..... I1 = index 1 ......

Here are examples in SQL Server http://msdn.microsoft.com/en-us/library/ms188783.aspx