It should be helpful to find each other in big crowds,and to find nearby rest centers .
You can thus upload your position with a nickname and privacy password (to prevent unknown people from getting your position).You can change your username and password anytime.
You can then search for each other with the known username and password.
If you have a rest center you can upload it and specify if food,shelter and toilets are available for pilgrims to know.
Specify its type as well.(police,medical,ordinary)