Gretl Manual: Gnu Regression, Econometrics and Time-series Library
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# Binary database details

A `gretl` database consists of two parts: an ASCII index file (with filename suffix `.idx`) containing information on the series, and a binary file (suffix `.bin`) containing the actual data. Two examples of the format for an entry in the `idx` file are shown below:

          G0M910  Composite index of 11 leading indicators (1987=100)
          M 1948.01 - 1995.11  n = 575
          currbal Balance of Payments: Balance on Current Account; SA
          Q 1960.1 - 1999.4 n = 160

The first field is the series name. The second is a description of the series (maximum 128 characters). On the second line the first field is a frequency code: `M` for monthly, `Q` for quarterly, `A` for annual, `B` for business-daily (daily with five days per week) and `D` for daily (seven days per week). No other frequencies are accepted at present. Then comes the starting date (N.B. with two digits following the point for monthly data, one for quarterly data, none for annual), a space, a hyphen, another space, the ending date, the string "`n =` " and the integer number of observations. In the case of daily data the starting and ending dates should be given in the form `YYYY/MM/DD`. This format must be respected exactly.

Optionally, the first line of the index file may contain a short comment (up to 64 characters) on the source and nature of the data, following a hash mark. For example:

          # Federal Reserve Board (interest rates)

The corresponding binary database file holds the data values, represented as "floats", that is, single-precision floating-point numbers, typically taking four bytes apiece. The numbers are packed "by variable", so that the first n numbers are the observations of variable 1, the next m the observations on variable 2, and so on.

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