Objective: MC approval of additional standard values for the HEADER_TYPE keyword. Date: 2003-08-19 Author: Steve Joy Background ========== Many of our data providers like to include a few lines of header material prior to the beginning of data in ASCII data files (tables, spreadsheets, etc.) because users find them useful. One line headers typically consist of column names. More detailed headers may provide additional information such as data processing parameters, input file names (such as SPICE kernel files), and other information. The current method of describing these headers is to call them tables with one column whose description is "Header text information". The PDS has a HEADER object that could be used to describe headers on ASCII files as headers, rather than as tables. In order to use the HEADER object in this way, we need to add TEXT to the standard value list of the required HEADER_TYPE keyword. Current Urgency =============== There is an existing work around to this problem that just confuses users and makes data providers complain about silly PDS standards. Recommendations =============== 1) Add TEXT to the list of standard values for the keyword HEADER_TYPE Impact ====== Minimal - PDS data dictionary update. PDS requires that all non-PDS headers be described by a document. I (S. Joy) will provide a brief document describing text headers. The document will state that text headers consist only of printable ASCII characters and are found attached to ASCII data files. I don't see any reason to be much more restrictive or descriptive about the formation and/or use of text headers. ----------------------------------------------------------------------------- PRODUCT_TYPE Data Dictionary Element Definition ----------------------------------------------------------------------------- OBJECT = ELEMENT_DEFINITION NAME = HEADER_TYPE STATUS_TYPE = APPROVED STATUS_NOTE = "V1.0 2003-08-19 SPJ Standard value update request." DESCRIPTION = " The header_type element identifies a specific type of header data structure. For example: FITS, VICAR. Note: In the PDS, header_type is used to indicate non-PDS headers." SOURCE_NAME = "PDS CN/S. Hess" GENERAL_DATA_TYPE = IDENTIFIER UNIT = "N/A" VALID_MAXIMUM = "N/A" VALID_MINIMUM = "N/A" MAXIMUM_LENGTH = "12" MINIMUM_LENGTH = "N/A" STANDARD_VALUE_SET = {BVD, FITS, GSFC_ODL, IGPP_FFH, SPREADSHEET, TEXT, VICAR, VICAR2} STANDARD_VALUE_TYPE = "DYNAMIC" DEFAULT = "N/A" FORMATION_RULE_DESC = "N/A" SYSTEM_CLASSIFICATION_ID = COMMON GENERAL_CLASSIFICATION_TYPE = STRUCTURE OBJECT = ALIAS ALIAS_NAME = "N/A" OBJECT_NAME = "N/A" USAGE_NOTE = "N/A" END_OBJECT = ALIAS OBJECT = LOCAL_ENVIRONMENT SQL_FORMAT = "CHAR(12)" TERSE_NAME = "N/A" END_OBJECT = LOCAL_ENVIRONMENT END_OBJECT = ELEMENT_DEFINITION