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All of the heights automatically rounded up or down on the last decimal (e.g., 1.534 m was automatically and [ostensibly] irreversibly converted to 1.5300 m in Matlab).
That's fine.
If a subject I thought I added does not show up, can I put it in?
Yes - firstly, if it does not show in the list, it's not in the database. Secondly, the database will not let you add a duplicate subject (i.e., cannot have two subjects with the same name).