Extracting one record from multiple-records textfile

Hello there. I'm a real beginner and I was wondering if you could be
so kind to help me on this.
I have a text file, containing a number of varying length documents,
all tagged with DOC-START and DOC-END, structured as follows:


DOC-START
content of the document
DOC-END

DOC-START
some text
DOC-END

DOC-START
rtreytgfbvb
DOC-END

DOC-START
sdfdf fdff ee
DOC-END

....

I need to take every document and pass it to a parsing function, that
accepts a file with *a single* document, that is

DOC-START
some text
DOC-END

My file contains lots of these records, so picking each document and
writing it into a new file is not an option. How can I extract the
documents one at a time from the file? Is it possible e.g. to put one
such record iteratively into a temporary file and pass this to the
parser?

Your help would be greatly appreciated.

Thanks
Giu

.