If you have long column labels with columns so wide that they affect the readability of a worksheet, you should first a. decrease the column widths. b. leave the column labels as is. c. consider how you could shorten the column labels. d. format the column labels.

The label at the top of a column is sometimes wider than the data stored in the column. Expanding a column is an option but this may mean that you will not see as many columns on a page as possible. Wrapping text is also an option but has a downside to it as well since it will make the row with great height. 

Rotating the labels is also a possibility but is also not recommended. This leaves us with shortening the column labels and keep dictionary worksheet for users. As much as you can, consider using acronyms and abbreviations.

do not use any of these common illegal characters/symbols:

# pound

% percent

& ampersand

{ left curly bracket

} right curly bracket

\ back slash

< left angle bracket

> right angle bracket

* asterisk

? question mark

/ forward slash

  blank spaces

$ dollar sign

! exclamation point

' single quotes

" double quotes

: colon

@ at sign