# Operator-Input Form for Lists?

The documentation on Operator-Input Forms shows the following example

which suggests that there is an alternative, convenient, operator-style, tidy technique for inputting lists. However, there is not enough clarity in the example to determine what that technique or operator might be. I tried e11Spacee12 and e11Tabe12, but they both result in Times[e1,e2], somewhat predictably, since space normally denotes multiplication in Mathematica notebooks.

Any ideas whether there is an operator form for inputting lists? What does the documentation mean in this case?

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Related: (761). This Q&A may also be of interest: (17004) – Mr.Wizard Jul 27 '14 at 16:41

To input lists, use Ctrl+, which creates two place holders like so:

You can move between them with Tab (forward) and Shift+Tab (backward), but not after you've entered a value. You can create a new column/element with Ctrl+, again and a new row with Ctrl+Enter.

You can use this form anywhere you need a list/matrix:

Documentation: Entering Tables and Matrices

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I wish I'd known this 25 years ago. I'm resisting my OCD telling me to go back-date the 25,000+ notebooks in my collection! – Reb.Cabin Jul 27 '14 at 16:35
@Reb.Cabin I'd personally stay away from using this for anything other than matrix input... using this form for lists will only lead to confusion (as you mentioned in the question, it could be misread as Times). – R. M. Jul 27 '14 at 16:44
Interesting that the documentation goo.gl/IyQMeF states this method obscurely: "Note that you can use... to start building..." [emphasis mine] after presenting the keyboard shortcuts as commands that "add" to a matrix or table that must presumably already exist, the only clue being that it states that "this" is often more convenient than the menu, without explicitly stating that "this" is "bypassing the menu." I'm looking for an excuse why I could have missed this for so long, so I'll criticize the documentation. – Reb.Cabin Jul 27 '14 at 17:12