// ARCHIVE HEADER
  4 - Header (APKF)
  4 - Unknown (263)
  4 - null
  4 - Padding (-1)
  4 - Unknown (2)
  
// DIRECTORY
  8 - Properties Directory Offset [+20]
  
  // DATA TYPE DIRECTORY
    // for each data type
      4 - Data Type (TEX + null, MAT + null, MESH)
      if (dataType == MAT){
        4 - Unknown (2)
        4 - Unknown (1)
        4 - Offset To The First Entry Of This Type in the Details Directory (relative to this field offset)
        4 - Number Of Files of this type
        4 - Unknown (16)
        2 - Unknown (0)
        2 - Unknown (-256)
        }
      else if dataType == TEX){
        4 - Unknown (3)
        4 - Unknown (2)
        4 - Offset To The First Entry Of This Type in the Details Directory (relative to this field offset)
        4 - Number Of Files of this type
        4 - Unknown (4)
        2 - Unknown (2)
        2 - Unknown (256)
        }
      else if dataType == MESH){
        4 - Unknown (2)
        4 - Unknown (2)
        4 - Offset To The First Entry Of This Type in the Details Directory (relative to this field offset)
        4 - Number Of Files of this type
        4 - Unknown (16)
        2 - Unknown (4)
        2 - Unknown (256)
        }
      else if dataType == SKEL){
        4 - Unknown (2)
        4 - Unknown (1)
        4 - Offset To The First Entry Of This Type in the Details Directory (relative to this field offset)
        4 - Number Of Files of this type
        4 - Unknown (16)
        2 - Unknown (0)
        2 - Unknown (-256)
        }
      else if dataType == ANIM){
        4 - Unknown (131350)
        4 - Unknown (1)
        4 - Offset To The First Entry Of This Type in the Details Directory (relative to this field offset)
        4 - Number Of Files of this type
        4 - Unknown (16)
        2 - Unknown (0)
        2 - Unknown (-256)
        }
      else if dataType == AEPS){
        4 - Unknown (1)
        4 - Unknown (1)
        4 - Offset To The First Entry Of This Type in the Details Directory (relative to this field offset)
        4 - Number Of Files of this type
        4 - Unknown (16)
        2 - Unknown (0)
        2 - Unknown (-256)
        }
    
    4 - null End Of Data Type Directory indicator
  
  // DETAILS DIRECTORY
    // for each file
      4 - Filename Offset (relative to the start of this field)
      4 - Hash?
      4 - Properties Directory Entry Length (TEX=68, MESH=244/808/404, MAT=704/160, ...)
      if (entry is TEX || entry is MESH){
        4 - File Data Length
        }
    
  // FILENAME DIRECTORY
    // for each file
      X - Filename
      1 - null Filename Terminator
      
  X - null Padding to a multiple of 4? bytes

// PROPERTIES DIRECTORY
  4 - Header (IMG + null)
  4 - null
  8 - Padding Multiple (16)
  4 - Properties Directory Length
  4 - Unknown (36/32/28)
  4 - Header (PHYS)
  4 - null
  8 - First Entry Offset (relative to the start of the Properties Directory (64) [-16]
  4 - File Data Length
  4 - Directory Length (including this field, but not including any of the fields before this one)
  X - null Padding so the Offset is a multiple of 16 bytes
  
  // for each file (TEX=68, MESH=244, MAT=704 bytes per entry)
    if (TEX){
      8 - null
      4 - Unknown
      4 - Hash?
      8 - null
      4 - Image Width
      4 - Image Height
      4 - Unknown (1)
      4 - Number Of Mipmaps
      4 - File Type (DXT5/DXT3/DXT1)
      24 - null
      }
    else {
      X - Properties
      X - Padding to a multiple of 16 bytes (Except for the last file of each type, which doesn't have this padding)
      }
  
// FILE DATA
  // for each file
    X - File Data
    
// FOOTER
  4 - Unknown (-1)
  
  // for each file
    4 - Unknown
    
  8 - Unknown (-1)

Some files are small and are stored in the Properties Directory, others (like TEX) are stored in the File Data at the end