There are several URLs, each corresponding to the available commands of our API, and thus through two different methods : type-entry and single line (thanks to /SINGLEV2 webservice).
Type-entry methods
Type-entry's objective is to close-up to your address starting by largest information to end-up with the most precise ones.
About "/CP" webservice
You have to use it to search for cities linked to a postal code, it proposes roads for municipalities with less than fifty.
There are two diferent ways of using it, you can either start typing the postal code in order to have the associated cities, or type in the city in order to be returned the associated postal codes.
1) If you want to add postal code before city, do not forget to add "Etendue" parameter. It allows you to search with at least two digits in Postal Code. Check out DQE Address' documentation.
2) If you want to search for cities before Postal Code this parameter is not to be added.
Technical documentation is giving you more details in part one and part two.
About "/ADR" webservice
It is used to search for streets linked to a city. This search should be initiated as soon as the city has been determined, it retrieves the address itself by suggesting the number, street type and street name closest to what final user is typing.
Learn more from the documentation.
About "/COMPL" webservice
This webservice can be used for additionnal address information but its search must be initiated as soon as the street and street number have been determined.
Typically it is used to specify a building number or a postal box number.
About "/LATLG" webservice
If you need to have precise location of the address you have entered, use this webservice. It returns latitude and longitude coordinates.
You must have used /ADR call before in order to retrieve accurate coordinates. To check how precise geoloc is, check out this dedicated article.
Single Line methods
About "/SINGLEV2"
This webservice is used to search an address from a single input field.
It is normal to have duplicates as we suggest several addresses for the same municipality.
First, it suggests possible number, street, city, postal code, and dependent locality, then you can select the accurate one without filling any other fields.
About "/COMPLV2"
This webservice gives additionnal information as "APT field" for example and is used in addition of /SINGLEV2.