INDIRECT() function in Excel

This is not a VBA issue but a recent discussion on LinkedIn brought up the question of how to use INDIRECT to construct a reference to a named range in an external sheet. I have been using this very useful function for years to programmatically construct references based on different parameters which resolve to a specific workbook, sheet, name etc. Here is some information on how to properly construct a text based reference.

INDIRECT returns a reference specified by a text string and the syntax is INDIRECT(ref_text [, a1]) where ref_text is a reference to a cell containing an A1-style reference, an R1C1-style reference, a name defined as a reference or a reference to a cell as a text string. An error in the reference returns #REF!. a1 specifies the type of reference and for TRUE or omitted means A1-style and FALSE means R1C1 style.

The INDIRECT function will return #REF! if the target workbook is not open at the time you open the source workbook (closing the target after it has been open doesn't cause this error as Excel remembers the value until you force a recalc).

The proper construction of a text string based reference is as follows:

'path[file]sheet'!range

where the literal characters apostrophe ', square brackets [] and exclamation mark ! delimit the following

• path = drive and folder where the file exists. If you leave this out then it will use the workbook named file you have open no matter its location on disk. If the path has a folder with spaces in it then you must use the apostrophes.
  
• file = the name of the file with extension. Use of the apostrophes means that this name can have spaces in it. If you leave out the apostrophes then no spaces are allowed!
  
• sheet = the name of the worksheet. Only use the "[]" delimiters if a sheet name is provided. No sheet name, no brackets around file!
  

If you don't provide a sheet name then the reference will default to the first sheet in the workbook. For a named range, no sheet will work if the named range has a scope of workbook or a scope of the first sheet. Obviously, if you provide a sheet for a named range then it must have a scope of that sheet or the reference doesn't exist and returns #REF!

I hope this is helpful to folks that are confused about this very useful function.