IBM DB2 On Cloud - How is table column name formatted?

[SE2097]

I have an IBM DB2 Cloud account and I have added DB2 from the catalog. I have a schema and I was able to create a table name.
I uploaded the data from a csv which has 1 row as header with column names.

I was able to successfully upload the data into the table, but for some column names it added underscore replacing space, where as in some column names it did not replace the space or special character.

Here are the sample column names where it updated column names with underscore and columns where it did not replace and loaded name as it is in the csv file.


Column in CSV File
==================================
School ID
Adequate Yearly Progress Made?
CPS Performance Policy Status
9th Grade EXPLORE (2009)
9th Grade EXPLORE (2010)
Elementary, Middle, or High School
====================================

After data loaded to DB2 - Column name
=======================================
School_ID
Adequate_Yearly_Progress_Made_
CPS_Performance_Policy_Status
9th Grade EXPLORE (2009)
9th Grade EXPLORE (2010)
Elementary, Middle, or High School
=======================================

If you compare the column names in some case the special characters and spaces are replaced with underscore and in some cases the column name is same as csv file.

Why this behavior?