10K is voltage compensated for VOH, VOL, and Vref (VBB) levels, but these levels vary with temperature. While 100K, VOH, VOL, and Vref (VBB) are both voltage and temperature compensated.
The 10K standard originally came from Motorola, I believe, and the 100K standard came from Fairchild.
I've attached a paper on 10K ECL and a beginners lecture on ECL.
I would also recommend searching the ON Semiconductor, which was has the former Motorola division that specializes in ECL/PECL products.
I would also recommend:
MECL System design handbook, which you should be able to get from ON Semiconductor. This was the "bible" for ECL designers.
In the book "Analysis and Design of Digital Integrated Circuits" by Hodges and Jackson, there is a chapter on ECL 10K and 100K circuit topologies.