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I sometimes see things like "野の風" be digested down into "野風" or "空の色" into "空色" both while retaining their meanings. When is this allowed to happen? What registers of speech? What sorta relationships? Is it only allowed for set phrases? etc. etc.
Why is 人権団体 not 人権の団体? Why is 人工言語 not 人工の言語? I'm simply curious, I've seen this so often.