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The five digits of precision alludes to an ASFixedNumberASFixed value. An ASFixedNumber ASFixed value is a hybrid of an Integer and a Real.


  • An integer is a binary number with bits encoding values from 0 to 2^32 (unsigned) or -2^30 to 2^30 (signed)
  • A real / floating point splits the bits between representing significant figures and a mantissa for the exponent

An ASFixedNumber ASFixed value shifts the meaning of the bits of a signed 32 bit integer value from representing 2^30 down to 2^0, to representing values between 2^15 (32,767) to 2^0.


For any number in a PDF that gets converted from a string to an ASFixed value, APDFL will read the full string. Given identical numbers before the decimal point, changes in the first four significant digits will result in the number being mapped to a different ASFixed value. If you also assume the first four significant digits are identical, then changes to the fifth digit can result in the number being mapped to a different ASFixed value, but that's not guaranteed. Anything beyond 5 digits won’t affect the number's representation as an ASFixed value. 

Because only almost five digits are significant, the The number is only guaranteed to be mapped to different ASFixed values for the first four significant digits. This is because the full five digits for the value are not significant; rather, almost five digits are significant. 

This means that numbers which are identical out to four significant digits, but have different fifth digit values, could be mapped to the same ASFixed value.