SEACOOS CDL v2.0 December 9, 2004 17 Scalar value of the same type as the variable. This attribute is not treated in any special way by the netCDF library or conforming generic applications, but is often useful documentation and may be used by specific applications.   Example: -9999 :source Text. Succinct characterization of the source of the data.   Example: “fixed-platform observation” :references Text. Article, book, or website reference used to describe the dataset andd/or collection program. Example: “http://comps.marine.usf.edu/” :history Text. An audit trail with a line for each invocation of a program that modifies the dataset.   Example: “Created by Data Manager” The following global attributes are recommended.  They were discussed by the DMCC but never approved or fleshed out in great detail to be required by any SEACOOS processing.  All of these global attributes are useful but not required. :process_level Text. Simple explanation of level of processing done to the data contained in the netCDF file.   Example: “raw data” :metadata_url Text. URL of metadata record where more supporting information about the data can be obtained. Example: “http://comps.marine.usf.edu/metadata/usfseacoos.htm” :start_date Text. Date and time stamp of first sample of data. Example: “2004-10-16 13:52:20 UTC” :end_date Text.  Date and time stamp of last sample of data. Example: “2004-10-18 13:28:19 UTC” :release_date Text. Date and time stamp for the release date of the data. Example: “2004-10-18 13:00:00 UTC” :creation_date Text. Date and time stamp for creation date of the data. Example: “2004-10-18 13:49:22 UTC” :modification_date Text. Date and time stamp for most recent modification date of the data. Example: “2004-10-18 13:49:22 UTC” :instrument_type Text. This attribute was initially intended to help describe the type of instrument or package of instruments used to collect the data in the dataset but can ultimately be deprecated by use of “:platform_code” and “ :package_code” attributes.  Example: “met”