I am looking at this question and it references a table with source and target columns. I am transitioning from another area of expertise and this makes little sense to me. I have a very established definition (example) of what I know this to be, but it doesn't fit the context at all.

I would like to comment: "What are source and target columns?"

I think this would be inappropriate since:

  • It would muck up his/her question and create confusion
  • I am sure that users of this board would know the answer and my clarification would add nothing to the answer
  • If people made a habit of of this activity, this site would become a mess of cross-links and change its structure

So what is the appropriate procedure in this situation? Asking a separate question of "What are source/target columns" in a separate question would have no context and be very confusing and likely downvoted.

  • 3
    Comments--like this one--are intended for such requests for clarification.
    – whuber
    Jan 20, 2013 at 20:21

1 Answer 1


When you are interested in a subject but find parts of a question unintelligible, then chances are other people will similarly struggle. Especially in GIS, people come from many different fields and backgrounds and thereby use different vocabularies to describe the same things (and the same words to describe different things!). It therefore is always a good idea to request clarification in the form of a definition or link to an established usage of any terms. You are likely to prevent a miscommunication.

In your example, the question is in a SQL context but seems to have something to do with "edges." One might then guess--without being completely sure--that "source and target columns" refers to how a mathematical graph is represented by a table in a relational database. This question thereby appears to bridge two different disciplines, abstract graph theory and relational database management systems. It is likely that few readers of this question--perhaps not even the original proposer!--will be well versed in both disciplines. You should not be afraid, then, to write a comment in which you (a) express your understanding of the key terms (as in the link you have provided) and (b) ask for clarification of the terms you are doubtful about.

(As a moderator of two technically oriented Stack Exchange sites, I daily have to write many comments in which I confess my ignorance or confusion. I view these comments as being among the most productive actions I take and wish more people would make the effort to write similar ones, because they directly inspire improvements to the questions.)

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