Sample 'file format' specification and applications for understanding issues in digital preservation. The format stores the information required for an eyeglass prescription for a single patient.
Eyeglass Format Specification 1.0
---
Magic number - 14 bytes - String
Version - 1 bytes - Unsigned Char
Big-endian - 1 byte - Bool
Date/time - 19 bytes - String #YYYY-MM-DDTHH:MM:SS
Expansion room - 88 bytes - Undefined
Sphere - 8 bytes - R: Float L: Float
Cylinder - 8 bytes - R: Float L: Float
Axis - 8 bytes - R: Integer L: Integer
Prism - 8 bytes - R: Float L: Float
Base - 8 bytes - R: Float L: Float
Distance acuity - 8 bytes - R: Float L: Float
Near acuity - 8 bytes - R: Integer L: Integer
Purpose - 140 bytes - String
Observation - 255 bytes - String
Next checkup - 4 bytes - Float
End of file - 4 bytes - String
The ‘magic number’ identifying the file format will be as follows:
'\xBB\x0D\x0A\x65\x79\x65\x67\x6C\x61\x73\x73\x1A\x0A\xAB'
The ‘end of file’ sequence terminating the stream will be as follows:
'\xBB\x65\x6f\x66'
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