Okay, so what the angle brackets mean in that context is something like "these characters should not be typed literally but instead tell you which characters you should be typing instead." So when you see this in the readme:
Code:
J2L_Tool SPLIT <level>
then, supposing you're working with e.g. mylevel.j2l, the readme is telling you that you should be typing:
Code:
J2L_Tool SPLIT mylevel.j2l
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