Constraints on the CRSH/CRNM ISO 8211 subfield

[FrankHippmann]

In B-5.1.10 of the S-101 Product Specification, the CRSH/CRNM ISO 8211 subfield is constrained to:

“WGS84” for horizontal CRS
“Depth - *” for vertical CRS where * is the name of the vertical datum

I note that the EPSG name for WGS 84 is "WGS 84" (i.e., including the space before the 84).

GEOGCS["WGS 84", DATUM["WGS_1984", SPHEROID["WGS 84",6378137,298.257223563, AUTHORITY["EPSG","7030"]], AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich",0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9122"]], AUTHORITY["EPSG","4326"]]

Based on S-100 Validation Checks check S100_Dev0214 (see also S-58 check 26a), a critical error is reported when the CRSH/CRNM subfield of a dataset does not conform to one of the above. There are production systems that use the EPSG name for WGS 84 to populate CRSH/CRNM, which results in a critical error, and the resulting dataset may be rejected by an RENC and/or ECDIS.

Given that CRSH/CRNM is a descriptive name only, and that CRSH/CRSI already uniquely identifies the datum, having a strict value constraint on CRSH/CRNM is considered unnecessary. The above constraint can be left blank or be replaced with a more general guidance, for example,

The name of the datum.

The S-100 validation check identifiers are under review and are subject to change. As such, the text to the relevant check is:

For each subfield whose value is not within the range of permissible values as defined by S-100 or the dataset's product specification.