Lines, logical records, are 80 bytes long. Contrary to typical use, the smallest independent entity in SBF is the block, not the logical record. In this regard, it is helpful to think of the block as consisting of one logical record. However, the division of the block into 80-character lines eases inspection of the block and, in many cases, simplifies data processing. Data elements are grouped chronologically into sets.
Several lines reside in each set.
A collection of sets, together with their block header, makes up the block. The number of elements in a set is exactly divisible by 8. When the number of data elements in the set does not fulfill this criterion, nulls are added to complete the set. The blocks are collated by time period and within the same time period by increasing element number, i.e., measurement parameter. Files group measurements of a specific time resolution from one station into significant time intervals, e.g., a month of Georgia Tech l-min data.