print to a specific location in a file

[Brian Volk]

Hi All~
 
Is it possible to open a file and print to a specific location in the file?
For example,  I have a 1K file and 0 - 511 is where the small description is
stored and starting in position 512 is the path to a pdf file....  If I do
not have the path in position 512 the link will be broken on web site.  Pls
let me know if this is possible and where I can read about it.
 
Thanks!
 
Brian Volk
HP Products
317.298.9950 x1245
 <mailto:[EMAIL PROTECTED]> [EMAIL PROTECTED]