All numbers on this documentation are in Decimal format.
Unless otherwise stated, values are stored as 4 byte Little-Endian Integers
A { and its paired } indicate insertions:
> Any Length followed by { <something> } indicates a string insertion
> Any value followed by a { on the next line indicates that the information between that { and its paired } is repeated the amount of times specified by that value.

*1* GM versions:
  520(dec) for GM5.3+
  500(dec) for GM5.0 - GM5.2
	(GM5.0 introduced lib files)

*2* Argument Types:
  0 Expression
  1 String
  2 Both
  3 Boolean
  4 Menu
  13 Color
  15 Font String
  5 Sprite
  6 Sound
  7 Background
  8 Path
  9 Script
  10 Object
  11 Room
  12 Font
  14 Timeline

GM version needed for the following info *1*
Length of Tab Caption { Tab Caption }
Lib ID (if ID < 1000, this file is protected as official)
Length of Author { Author }
Lib Version
(double) is the "Last Changed:" time - days since 1899-12-30
Length of Info { Info }
Length of Initialization Code { Initialization Code }
Advanced
Number of actions (changes to a different number in official libs.)
Number of actions again
{
  GM version needed for the following info *1*
  Length of Name { Name }
  Action Id
  Image size { Image Data (bmp format) }
  Hidden
  Advanced
  *Registered only (* - excluded in version 500)
  Length of Description { Description }
  Length of List Text { List Text }
  Length of Hint Text { Hint Text }
  Kind (values are 0-10)
  Interface Kind (0=Normal, 1=None, 2=Arrows, 5=Code, 6=Text)
  Question
  Apply to
  Relative
  Argument Count
  Number of Arguments (always 8)
  {
   Length of Argument Caption { Argument Caption }
   Argument Type (0-15) *2*
   Length of Default Argument Value { Default Argument Value }
   Length of Menu { Menu }
  }
  Execution Type (0-2)
  Length of Function Name { Function Name }
  Length of Code { Code }
}