Overview
ISO 7168-2:1999 - Air quality - Exchange of data - Part 2: Condensed data format defines a compact, machine-oriented file format for exchanging air quality data between automatic data‑processing systems. Unlike the human‑readable general format in ISO 7168‑1, the condensed data format reduces file size and is restricted to the minimum information necessary for automated processing. The standard specifies file structure, character encoding, field formats, file‑naming conventions and a set of normative annexes (A–D) with codes and representations.
Key topics and technical requirements
- File structure: Data files are divided into four groups - identification, description, data, and comment - each with specific record types and expected contents.
- Character set and control codes: Uses the 7‑bit international information exchange code (ISO/IEC 646). Lines must start and end with a return‑to‑new‑line (RNL) code (LF + CR) to support cross‑platform processing.
- File naming rules: File names are limited to 8+1+3 characters and constructed from parameters (see Table 1): station code (SSSSS), date elements (YY, MM, DDD), optional unused fields (X) and a file qualifier (Q) indicating internal status (e.g., V = validated, U = unvalidated, I = internal incomplete). Examples in the standard show daily, monthly, annual and multiannual naming patterns.
- Data presentation formats: Defines fixed numerical (N), fixed alphanumerical (A) and variable alphanumerical (V) field formats, plus explicit time formats (YYMMDDhhmm) and geographic fields (latitude/longitude/altitude) referenced to Annexes C and D.
- Air quality data encoding: Values are transmitted as integers with an associated exponent (base 10) to express units (per ISO 4226 / ISO 1000). Every datum is paired with a data qualifier code (e.g., U = usable, N = no datum, E = estimated, F = faulty) that indicates validity or special conditions.
- Normative and informative annexes: Annexes A–D are normative (character set, measurand codes, geo data presentation, coding of data types), while E–G provide informative examples, file structure diagrams and sample data files.
Applications and users
- Who uses it: Environmental monitoring agencies, air quality data managers, instrument manufacturers, software developers, regional networks and researchers exchanging bulk measurement data.
- Practical uses: Automated transfer of hourly/daily/monthly measurements between monitoring stations and databases, integration of sensors into national reporting systems, compact archival exchange for bandwidth‑limited links, and standardized imports for analysis pipelines.
Related standards
Keywords: ISO 7168-2, air quality data exchange, condensed data format, file naming, data qualifiers, measurand codes, automated data processing.
