What function does this で have


For full context, see
[here](https://www.docdroid.net/bv19a5D/img-20170817-0001-new.pdf).

It is in paragraph 2, example:

> 同じ色で違うサイズのシャツを探す。  
>  => "Someone looks for a shirt of different size and being the same color"

I interpreted it as the continuative form of です, but in this case, at least
from a conceptual perspective, it could just as well be the particle で.

> "Someone looks for a shirt of different size with the same color."

That's why I wanted to ask for confirmation whether I'm right or not.




The most straightforward interpretation is the continuative form of だ, as you
say. (Technically, that of です is でして.)

That said, you can also interpret it as particle で in the sense of "under the
condition of the same color (one looks for)".

"With" as in "a shirt of different size with the same color" directly modifies
the noun "shirt" but particle で doesn't work that way without の. However,
there's a room to interpret that it indirectly modifies シャツ through ちがう, which
receives 色で and modifies サイズ, which modifies シャツ.

