This is what I've gleaned from examining the binary keyword.bas
files generated by Ulead's Photo Explorer.  This is enough to read
the captions out of the files, and that's all I cared about, so
that's all I bothered to decipher.

bytes 0-4:   4-byte integer indicating number of images in file

each record:
  259 bytes: filename plus unknown binary content
    the filename comes first, null terminated.  So if the filename is 10 characters
    long, you'll have the 10 characters of the filename, a null character, and
    then 248 random bytes

  caption length indicator:
    0x00 to 0xfe - single byte value of the caption length
    -OR-
    0xff: means to read the next two bytes as the caption length

  caption