Proposal to clarify that in the case where telltale No. 1 (Master lighting switch) and telltale No. 19 (Position, side marker, and/or end-outline marker lamps) are combined, the symbol may be shown in other colours than specified in the table of telltales in order to convey different meanings according to the general colour coding as proposed in paragraph 5. of ISO 2575-2004 (i.e., per footnote 18 to the table).
49. The expert from OICA presented ECE/TRANS/WP.29/GRSG/2017/18 to clarify footnote 18 where tell-tales Nos. 1 and 19 were combined. Some experts were of the opinion that footnote 12 already offers that possibility. Following the discussion, the expert from OICA offered an alternative proposal GRSG-113-39 that simplifies the handling of colour changes of tell-tales and to remove footnote 18 and all references to it. The expert from France preferred to keep the existing text of footnote 18 and to only insert under symbol No. 1 a reference to footnote 18, as reflected in GRSG-113-42. GRSG agreed to go forward with a two-step approach and adopted ECE/TRANS/WP.29/GRSG/2017/18 as reproduced below.
| No. | Column 1 | Column 2 | Column 3 | Column 4 | Column 5 |
| Item | Symbol 2 | Function | Illumination | Colour | |
| 1. | Master lighting switch
|  1, 18 | Control | No | |
| Tell-tale 12 | Yes | Green |
50. The secretariat was requested to submit the proposal to WP.29 and AC.1 as draft Supplement 10 to the original series of amendments and Supplement 3 to the 01 series of amendments to UN Regulation No. 121 for consideration at their March 2018 sessions, subject to the endorsement of the Working Party on Lighting and Light Signalling (GRE) at its October 2017 session. (Note by the secretariat: At its seventy-eighth session, GRE endorsed the principles for amending UN Regulation No. 121 as proposed by GRSG.)
51. As a second step, GRSG requested the secretariat to distribute GRSG-113-39 with an official symbol, for consideration at the next GRSG session and to also circulate it all WP.29 Working Parties concerned.
39. The expert from OICA introduced GRSG-112-24 to clarify the application of footnote 18 in the case where tell-tales Nos. 1 and 19 were combined. Some experts were of the opinion that footnote 12 already offers that possibility and that the proposed amendment was superfluous. GRSG agreed to take a final position on this subject at its next session and requested the secretariat to circulate GRSG-112-24 with an official symbol.
| GRSG/2017/18 |