From ESTA.org and supported by http://www.esta.org/tsp/working_groups/CP/projs.html and http://www.sandsys.com/acn/sandnet_acn.htm :
BSR E1.31, Lightweight streaming protocol for transport of DMX512 using ACN.
But on http://en.wikipedia.org/wiki/DMX512-A there are an other description under the heading "Development":
ESTA has initiated a project numbered E1.31 to define an interoperable CAT5 transport for DMX512.
This probably should not refer to transferring the data bytes of DMX over IP networks, not EIA485 electrical signals over twisted pair of CAT 5 quality.
Entertainment Technology -- USITT DMX512-A -- Asynchronous Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories . See DMX
The above is found via http://webstore.ansi.org/
Note that DMX512-A was updated in 2004 and again in 2008: http://www.esta.org/tsp/news/newsdetails.php?newsID=291 (regarding text mesasges in UTF-8, update rate almost up to 20*44 Hz, corrections of errors and clarifications)
The drafts for new standards seems to be made by ESTA who has this list currently:
E1.31 covers basic DMX through ACN, and E1.33 will extend E1.31 to include RDM data transmissions. Ref: News from USITT http://www.usitt.org/sightlines/v46/n10/stories/EstaNewStandards.html#dmx which is also cited here 
The RDM protocol is to be extended with BSR E1.37 e.g. for bulk data transfer.