encoding of image size on mms header

[pautamo]

85 1A, last octet begins with zero.
M, Forum Nokia

[qvick]

I have a jpeg image let's say size of 666 bytes. How do I encode it in mms multipart message header?

My trial is: 84 a3 01 01 85 9a 9e ff ...
01: only one part in message
01: multipart header will contain only one byte (content-type)
85 9a: size of data (jpeg image) encoded as bytes where each of them contain 7 bits of the size and most significant bit set to 1
9e: content-type (image/jpeg)
ff ... contents of image file

right?