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Section 5

Data Representation

Primary and extension data shall be represented in one of the formats described in this

section. FITS data shall be interpreted to be a byte stream. Bytes are in big endian

order of decreasing significance. The byte that includes the sign bit shall be first, and

the byte that has the ones bit shall be last.

5.1

Characters

Each character shall be represented by one byte. A character shall be represented by its

7-bit ASCII [20] code in the low order seven bits in the byte. The high-order bit shall

be zero.

5.2

Integers

5.2.1

Eight-bit

Eight-bit integers shall be unsigned binary integers, contained in one byte with decimal

values ranging from 0 to 255.

5.2.2

Sixteen-bit

Sixteen-bit integers shall be two's complement signed binary integers, contained in two

bytes with decimal values ranging from -32768 to +32767.

5.2.3

Thirty-two-bit

Thirty-two-bit integers shall be two's complement signed binary integers, contained in

four bytes with decimal values ranging from -2147483648 to +2147483647.

FITS Standard