At commands using in i2c

i am beginner to developer studio tool. I am using Open_AT_Application_Framework_v2-51_Full_Installer downloaded from sierra site.
I have been used sample application from the Developer studio. In i2c application you are using AT+READ,AT+WRITE,AT+SETMODE like that at commands. In the at firmware guide ,wip at guide the commands are not avilable.Where can i able to see those type of commands or these are created by user? can you explain me

Which sample, exactly :question:

These are Custom commands created by the application.

They are described in the Documentation (HTML file) for the sample.

Yes - see above!

I am using sample projects given in Devstudio, New-> openATproject->New open AT project->Target platform configuration->Sample selection->externalstorageI2C

In this sample lot of ADL functions like adl_atCmdSubscribe();adl_InitGetType ();adl_atSendStdResponse (); etc, are used in which file shall i get definition of these function? or else those functions arepredefined.

All ADL functions, and associated data types, etc, are documented in the ADL User Guide.

Also in the Open-AT tutorial book.