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The Singer 99k is a straight stitch only machine. You can't do detailed embroidery on it, or even a zigzag stitch. Singer did invent a zigzag attachment for their machines, but I have hear they are bulky and awkward and hard to get good results.
Despite being only straight stitch, the 99k is still a lovely machine, built far better than the plastic stuff nowadays. It has a beautiful stitch.