What can the variable data be used for in this case?

[gaeVG]

ESX_Documents/client.lua

Line 245 in d4517b8

end, data)

On the server side, the variable is not used, is this normal?

ESX_Documents/server.lua

Line 85 in d4517b8

ESX.RegisterServerCallback('esx_documents:getPlayerDetails', function(source, cb)