Update data_review.Rmd

Author: ml-ebs-ext

vignettes/data_review.Rmd

@@ -78,7 +78,7 @@ The `review` parameter is itself divided into four subfields:
   - `id_vars`: `[character(n)]` Immutable variables that uniquely identify each record for a given domain. For example, in the case of the demographics domain, the **U**nique **SUBJ**ect **ID**entifier is enough. In the case of the adverse events domain, both USUBJID and the **A**dverse **E**vent **SEQ**uence number are necessary.
   - `tracked_vars`: `[character(3+)]` Variables to track across dataset updates. If the contents of one of this columns changes on an already reviewed row, that review will be marked as potentially outdated. This vector should list at least three variables.
 - `choices`: `[character(n)]` Review choices available to assign to each listing row.
-- `roles`: `[character(n)]` Names of reviewer roles.
+- `roles`: `[character(n)]` Names of reviewer roles. These names can only include the following characters: alphanumerical, space, dot, underscore and dash.
 - `store_path`: `[character(1)]` Optional. If specified, files associated to the review process will be stored on this path on the server. If left unspecified, those files will be stored on a folder of the _client_'s computer. The users of the app will have the opportunity to choose the path when they launch it.
 
 ## Storage of review-related files