When you subscribe a custom command, you specify the minimum & maximum numbers of parameters;
for the purpose of this count, omitted parameters are included.
Example:
AT+MYCMD=1,,2is considered to have three parameters for the purpose of meeting the maximum/minimum parameter count criteria
But, when this command is delivered to the Handler, its number of parameters will be given as two 
And, if you use ADL_GET_PARAM, you will have to retrieve the first and third parameters - even though the count says there’s only two