# ECEF and ECI tags, do we need them? Frames seems to be the standard

I was adding tags to Satellite tracking telescope integrated program in Matlab and included the tag with 24 questions.

Then I noticed there also existed with 5 questions, and with 2 questions that are also tagged eci.

It seems that those 5 could easily be covered by the frames tag and that we don't need the two more specific ones, very often people want to convert between one and the other.

Shall I just retag the five with frames and let the eci and ecef sort-of disappear when the clock strikes twelve?

update: I'm going to open up this question a little by mentioning that the tag is also being actively used in this constellation of concepts:

• Thanks, was unaware of "frames" tag. – Organic Marble Nov 7 '20 at 0:04
• feel fee to add additional examples – uhoh Nov 7 '20 at 3:14
• See the end of this answer space.stackexchange.com/a/20271/6944 for examples of frames used in robotics ops. – Organic Marble Nov 7 '20 at 3:28

So this was originally a really short yes, and I realize now that was unclear. I had intended it to be a "yes" to uhoh's last question about retagging. After Pearson's comment, I've changed my mind. It seems maybe we should deliberate longer to find a better solution that doesn't wipe out more familiar terminology.

• If there was an easy way to combine ECI and ECEF, merging those two would be fine. But I personally use ECI and ECEF frequently in my work, I've never even heard the term "frame" to combine them. So yeah, I agree with this. – PearsonArtPhoto Nov 6 '20 at 21:03
• Well I relish being wrong and getting egg on my face because it means I learn something! Let's see where this goes: Are ECI and ECEF both frames and/or coordinate systems? Is there a difference? It's just that I don't want to get relish on my face. – uhoh Nov 7 '20 at 0:22
• I've opened the question up to include the coordinates tag, which seems to have been used for the same purposes and exclusively of frames several times – uhoh Nov 7 '20 at 3:16
• under my question linked in my comment above @astrosnapper has linked to naif.jpl.nasa.gov/pub/naif/toolkit_docs/Tutorials/pdf/… Briefly, a frame is what we think (inertial or non-inertial) it is and a coordinate system is a set of instructions for how to use the frame, – uhoh Nov 7 '20 at 4:01
• @uhoh From the results of that discussion, it looks to me like we need to keep all the tags. I know some of them only have a few questions, but I think having the tags will be genuinely helpful for categorizing as we get more questions, even if they have a lot of overlap. Someone may search for one term and not think to search for the other, and they are not close enough in meaning to make synonyms, IMO. – called2voyage Nov 9 '20 at 15:04
• @called2voyage I'll agree that if someone starts typing eci or ecef that the frames tag should be suggested for them since they might not know about it, but having all four tags (eci, ecef, frames, coordinates) will lead to tagging-fragmentation. If I'm looking for questions about a transformation between eci and ecef, I have to search all four tags separately to find them. I'm looking for consolidation to make answers more findable. What I don't know is how much tags are actually used for searches now and in the future. If tags matter then such fragmentation is bad. – uhoh Nov 9 '20 at 15:09
• At a bare minimum, as soon as they start typing eci or ecef the little blurb of text that appears with the autocomplete should start with "also consider using frames". – uhoh Nov 9 '20 at 15:10
• @uhoh And that's a valid concern, I'm just not sure making eci and ecef synonyms of coordinates or frames alone is the way to go. There are some things that are just hard to handle in the tagging system we have, especially when the concepts are just starting out. – called2voyage Nov 9 '20 at 15:11
• @uhoh That's a good idea to add something to the excerpt. They definitely all need adequate excerpts. – called2voyage Nov 9 '20 at 15:11
• @called2voyage Can you describe a real-world hypothetical example scenario in which "making eci and ecef synonyms of... frames" would be a problem? – uhoh Nov 9 '20 at 15:13
• @uhoh from one of the answers to your question, you can see that technically they are coordinate systems, so I think the thing that makes the most sense is to add them as synonyms to coordinates, but then you can't also make them synonyms of frames, which they are colloquially referred to as. That's the problem. – called2voyage Nov 9 '20 at 15:14
• @called2voyage Okay, how about making all synonyms of coordinate systems? Or frames-and-coordinate-systems now that tags can be longer? – uhoh Nov 9 '20 at 15:15
• @uhoh coordinates already has 49 questions--you're losing topic granularity at that point, but it's not necessarily a bad thing. I think it would require another meta question to decide on that action though. – called2voyage Nov 9 '20 at 15:16
• I call it fragmentation, you call it granularity :-) I suppose there is a balance. – uhoh Nov 9 '20 at 15:17
• @uhoh Yes, there is definitely a balance. Otherwise all questions would be tagged with space. lol – called2voyage Nov 9 '20 at 15:18

These two systems are fundamentally different and refer to two different things, and if I understand the question correctly, it is not possible to merge and combine their tags.

• My thinking is that they are both already captured under the Frames tag. If you notice there are only 2 questions out of 14,079 that have the ECI tag, and both of those also have the ECEF tag, and since we have quite a glut of tags and the moderators and several users have been working hard to clean them up a bit, these two don't have a beneficial function, and we will be fine with only the Frames tag. – uhoh Nov 7 '20 at 0:03
• So if I remove ECI and ECEF from those five questions, they'll all still be tagged Frames and the two highly specific and rarely used tags will become invisible in 24 hours. I propose that in addition to Frames, we don't need them. – uhoh Nov 7 '20 at 0:04
• HOWEVER there seems to be some concern now, so I've just asked Are ECI and ECEF both frames and/or coordinate systems? Is there a difference? – uhoh Nov 7 '20 at 0:21
• I've opened the question up to include the coordinates tag, which seems to have been used for the same purposes and exclusively of frames several times – uhoh Nov 7 '20 at 3:15