File IDs and File-set IDs shall be character strings made of characters from a subset of the G0 repertoire of ISO 8859. The following characters form this subset:
A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z (uppercase)
1, 2, 3, 4, 5, 6, 7, 8, 9, 0 and _ (underscore)
Notes: 1. This is the character set defined for Control Strings (Value Representation CS - see PS 3.5 of the DICOM Standard) except that SPACE is not included.
2. This character set is selected to limit characters in File IDs and File-set IDs to those that do not conflict with reserved characters and delimiters in the file systems defined in PS 3.12. Component delimiters or other required demarcations defined in PS 3.12 are not part of File IDs or File-set IDs