This GridOption lets you choose for each DiaryGridLine, what delimiters to use for filler tokens.
The 3 possible choices are:
| \ and / _ and - ` and ^ |  | 
The reason why there are 3 possible pairs of Filler Delimiters is that they are often used to separate the result of 2 tokens, sometimes with a front slash / and sometimes with a hyphen - (and sometimes, though it is not an issue, with a bullet •).

Other than that, another common use for Filler Delimiters and Filler Tokens is when displaying tokens that are sometimes blank, such as holidays tokens or moon phases tokens.
| In the example, on the right, if you separate the 2 tokens with a space, then you have an extra space to the left of the moon phase when there is no holiday. |   |  | 
| The solution is to use filler tokens and write [fa\/ ][mp] to have a space to the right of the holidays, only if there is a holiday. |   |  | 
Forgetting to select the proper delimiters, leads to a token not found message at run-time.
Topic 155100, last updated on 01-Aug-2020