What is an additional attribute in loadrunner vugen?(RUNTIME SETTINGS IN VUGEN)

Additional attribute is a run time setting in VuGen and controller in loadrunner. This is used for reading a attribute value from run time settings.
This will be helpful, to pass any value to the test script from run time settings. This will overcome the limitations of parameters in VuGen. The parameters can be read and edited from the VuGen script only. Cannot be edited from controller.
If you want pass some value to the script from controller, we use additional attributes. Since additional attributes are part of run time settings, so it can be passed from controller. But there should be corresponding functions written in VuGen script to read the values.

Additional Attribute:
char *cache1;
char *cache2;

cache1=lr_get_attrib_string("Cache_Param1");
lr_save_string (cache1,"NewCache1");

cache2=lr_get_attrib_string("Cache_Param2");
lr_save_string (cache2,"NewCache2");

In Performance center Command line argument:
-Cache_Param1 "http://tkodclxgfa1stg003.lehman.com:19000"

Note:Cache_Param1 is the string that will give in Run-time setting.