1.1.4 Implementation limits

The following rules are not a part of the PDF specification, however you should respect them to achieve maximal compatibility with PDF viewers / editors:

• Integers should be in the range between -2'147'483'648 and 2'147'483'647
• Floating point numbers should be in the range between -32'767 and 32'767 and should not contain more than 5 decimal places
• Arrays should not have more than 8191 entries
• Dictionaries should not have more than 4095 entries
• Strings should not be longer than 65'535 bytes
• Names should be at most 127 bytes long
• A PDF should at most contain 8'388'607 indirect objects

A bit more detailed:

• Sub-arrays and sub-dictionaries only count as a single entry in the parent array / dictionary
• In strings, only characters that are visible to the user count (backslashes do not count as characters). One character needs one byte for a simple character access, two bytes for a complete character access (see "Full character range" in the chapter "Advanced Typography").
• In names, hex-coded characters are counted as one byte. All other characters, including the preliminary backslash, count as one byte.

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