christian.laurent

hi Yaron, I try to understand and to clarify the situation. So, coming back to your 1st post: I fully understand your points, viewed from your own specific context of today. Most probably, your assumptions above are based on your own applications you live with every day but they do not match with the general historical intend and use cases of the DCS tags, as I tried to describe below. Below, the stars **** refer to the discrepancy refered with the corresponding stars **** from your text above. 'ER' (= engraving reference point) that appeared in DCS 3.03 to my knowledge (where no engraver<>(****) was taken into consideration yet) is neither reserved for engraving <>(****), nor for the back <>(*): the tags ERNR and ERDR were and are still providing distances for NV and FV measurements, including for traditional PAL’s already engraved <>(****) on the front.<>(*) To use FB as a reference for ENGMARK (as mentioned above) is again for a very very specific application. Most systems are not using FB as a reference for inking or engraving.<>(**) So, most often 'engraving point' 'ER' refers to an already existing (not to be engraved (***) (****) ) permanent positioning reference marking used to position the lens or as reference for finding another point. Many DCS tags are not taking 3D aspects into consideration for historical reasons, considering often there is no parallax effect: the lens in some way is behaving like a flat thin lens, with no difference between front and back engravings <> (*) for example. BE, with the ‘B’ for 'back' provides more clear 3D information: I have the feeling that it can be considered as a reference point (-> DCS table 2) anyway, but the ‘B’ for 'back' differentiates the specific use of this point for a 3D approach. So, I think you are reconsidering what is done since 20 years. Anyway, I would like to better understand your concern. Maybe, for our understanding, you could illustrate what are the tags you are using that involve 'ER'. TY in advance. Again, I do hope this helps.

Yaron, are you sure you are marking according to the finishing (=edging) block (-> FB) and not according to surface block (-> SB) ? TY for confirmation.

Hi Yaron, Someone might discussed about the seIected name, but I had the feeling that the définitions and descriptions from the proposed draft were quite clear regarding the use cases (without ambiguity): Table 2 BE: Back Engraving Reference Point (“BERP”); midpoint between semi-visible alignment marks on the back surface of backside engraved lenses; origin of the back surface reference coordinate system. Table 3 BEOCA, BEOCIN, BEOCUP: Back Engraving Reference Point on the back surface to Prism Reference Point on the front surface after engraving cla: “front surface after engraving” can be confusing – > “front surface for backside engraved lenses” or simply remove “after engraving” (the definition BE/BERP is clear from table 2) and particularly with: 5.2.2.1 ... Note Most distances and orientations on a lens are defined according to a reference coordinate system on the front. For backside engraved lenses, the lens reference coordinate system on the front is linked to the reference coordinate system on the back as described in 5.2.4. As a conclusion: - from the note in 5.2.2.1 mentioned above and "Most distances and orientations on a lens are defined according to a reference coordinate system on the front. ", (working in fact in a single plane (OFXFYF)) , one get a commutative behaviour. - we introduced 3D aspects here with BE at the origin of a new, different coordinate system named "reference coordinate system on the back", without commutative behaviour between points in different coordinate systems - BE being a reference point anyway. I do hope this will help to clarify.

Hi Yaron, referring to your second message, and: I have to say we never engrave or ink lenses on the finishing (=edging) block block.

Hi Yaron, you mentioned above: " answers/discussion on #1 are needed, it's an open topic. " So, I tried to understand your concern #1, particularly regarding (from your message): "On the other hand, so far in practice from our customers, whenever front-side/finishing engraving isn't done relative to frame (which it usually is, so doesn't matter so much), they expect it relative to FB. But from Christian, they report to use the PRP (Reference Point OC) as center for marking on the front side on a finishing block. (So difference of FBOC__ )" , please be more explicit for both sentences, particularly for the second one. - "from Christian": (when, where?) - "they report" = who report ??? - "marking" = engraving operation? (permanent marking, not inking)??? - "on the front side on a finishing block" = on the front side of a lens held on a finishing block ??? TY !