How does silent install determine what feature are selected to be installed?
I have noticed the following:

1. Console mode:
I able to check the contents of the variable:
Value of: CHOSEN_INSTALL_FEATURE_LIST is: $CHOSEN_INSTALL_FEATURE_LIST$ result is: SRVAPIAP (this is the feature i selected to install)

from the above Console run, i created a response file, that i can see contains:
#Choose Install Set
#------------------
CHOSEN_FEATURE_LIST=SRVAPIAP
CHOSEN_INSTALL_FEATURE_LIST=SRVAPIAP
CHOSEN_INSTALL_SET=(Custom)

2. Silent mode:
Value of: CHOSEN_INSTALL_FEATURE_LIST is: $CHOSEN_INSTALL_FEATURE_LIST$ result is: no value
However the installation proceeds successfully.

I would think in silent mode the variable values are loaded from the response file.
How then does silent install determine what feature are selected to be installed?
Note: For Console and Silent install, I output value of CHOSEN_INSTALL_FEATURE_LIST to a file on my desktop.