General transcription factors vs. DNA Binding transcription factors
When we say trans we mean that a diffusible factor, or agent is involved. So a molecule synthesized at one location, that can have a regulatory role in another location in the cell is said to be a "trans-acting" factor.

When we say cis we mean physically linked to, in such a way that the biological regulation only affects other molecules that are attached (in other words, something that is "cis-acting" cannot be freely diffusible).

So prokaryotic operators or promoters, and eukaryotic enhancers and promoters would be examples of cis-acting sequences, or elements.  All protein transcription factors, or even DNA-binding proteins, are therefore trans-acting.