Question

I know what they mean, but I couldn't find a way to ask the question, but does it mean that I can only make a deck with the same symbols of the cards?

Comments

I think Its the symbols of the expansions, and yeah I think you can use different ones.
 (Its not definite that is why I did not make it an answer)

Answer 1

http://pokemondb.net/pokebase/57929/what-is-the-marking-in-the-bottom-right-corner-for-in-the-tcg

Those are symbols to tell what set the cards are from. A checkered box for example is for the Black&White set.

The only current restrictions on cards you can use are that they must be from Black&White or later.