GCA stands for General Currency Area. The list of GCA countries is all countries, excluding some rupee currency countries.

All countries other than Nepal, Bhutan and former USSR fall under General Currency Area.

Take a look at the Wikipedia article "List of countries and dependencies by area".

www.wtng.info is the most comprehensive resource for this.

If you list all the countries of the world in order by land area, from the largest to the smallest, the area rank is the number on the list for that particular country. The largest country is #1, the next largest is #2, and so on.