What we consider experimental music WITHIN the greay-area context (key word being "within") or within the context that Chain D.L.K. deals with, is usually really weird stuff, people who make music/sounds experimenting with "things" never done before, trying to find new ways to produce sounds, charting uncovered territories etc etc...
Take a look at the Experimental Music category in the Reviews section and read some of the record's reviews to understand what kind of unhortodox stuff we label as "experimental"... Personally, when I say experimental, the Belgian label Staalplaat is the first things that comes to my mind, but there are a number of other labels and artists producing challending or interesting new things... In my experience I have come across so many things that could not have been otherwise classified, if not using the term experimental... for example, how would you otherwise call a record made of the amplified sonics originated by a building or other structure and recorded with microphones to record earthquakes and other subsonic sources? or what would you call music made with the amplified sound of brainwaves? or an entire album where you think you hear keyboards, vocals, guitars, but all that has been used to create those sounds was a bass? or even a record where a pipe organ has been filled with combustible liquid and every note you play on its keyboard triggers an explosion pitched according to the size of the pipe where the explosion takes place in? or what about albums made of provoking silence? or even old hits re-created on an old computer, a self-written text-to-speech software and a truly shitty sound card?
I could go on and on about the weirdes things that crossed my path during the last 10 years... This just gives you a taste of how we use the term experimental here... Of course it is not an exclusive term, and like said before, it can be applied to different contexts, but it helps to consider the term "within" a context and to use it to describe things that are relatively experimental as opposed to absolutely experimental... Personally I consider the stuff I mentioned above really quite unique, but maybe in the future all the music we will hear will be made with brain waves as opposed to instruments, so what can I say? What is experimental now might not be experimental anymore in the future in the same way that some music of the past was experimental and is not considered experimental anymore today... After all, isn't everything relative, like the good old Eintstein said?