To my knowledge, there is no one method that is standardized. Most of the more modern recordings will be multi-miked with many mikes placed all around the orchestra. Then this is all mixed together in the mixing booth.
Back in the good old days, when they knew better, they placed a single pair of Neumann tube mikes suspended from wires above the audience's head at about the 6th row. One for each channel, from the prime listening position. This is a super way to mike, because all the stereo information is phased correctly, and needs no "playing around" in the mixing booth. You actually hear the instruments in their proper positions in the orchestra, and they are correctly balanced just the way you would have heard the performance live. Many of the old Mercury Living Presence recordings were done this way, and that's why people want them so much. Sure, there were other limitations, but the presentation was correct, at least. I can't listen to many of the newer multi-miked classical recordings because they have the instruments imaged out of whack.
Back in the good old days, when they knew better, they placed a single pair of Neumann tube mikes suspended from wires above the audience's head at about the 6th row. One for each channel, from the prime listening position. This is a super way to mike, because all the stereo information is phased correctly, and needs no "playing around" in the mixing booth. You actually hear the instruments in their proper positions in the orchestra, and they are correctly balanced just the way you would have heard the performance live. Many of the old Mercury Living Presence recordings were done this way, and that's why people want them so much. Sure, there were other limitations, but the presentation was correct, at least. I can't listen to many of the newer multi-miked classical recordings because they have the instruments imaged out of whack.