diff --git a/README.md b/README.md
index f544fcc6..81561c58 100644
--- a/README.md
+++ b/README.md
@@ -21,11 +21,11 @@ All data is stored in the [/data](data) folder as [CSV](https://en.wikipedia.org
 | network        | Name of the network operating the channel.                                                                                                                                                                       | Optional | `NBC`                         |
 | country        | Country code from which the channel is transmitted. A list of all supported countries and their codes can be found in [data/countries.csv](data/countries.csv)                                                   | Required | `US`                          |
 | subdivision    | Code of the subdivision (e.g., provinces or states) from which the broadcast is transmitted. A list of all supported subdivisions and their codes can be found in [data/subdivisions.csv](data/subdivisions.csv) | Optional | `US-CA`                       |
-| city           | Name of the city from which the channel is transmitted                                                                                                                                                           | Optional | `San Francisco`               |
+| city           | Name of the city from which the channel is transmitted. May only contain `a-z`, `à-ÿ`, `0-9`, `space`, `-`, `'`.                                                                                                 | Optional | `San Francisco`               |
 | broadcast_area | List of codes describing the broadcasting area of the channel. Any combination of `r/<region_code>`, `c/<country_code>`, `s/<subdivision_code>`                                                                  | Required | `s/US-CA`                     |
 | languages      | List of languages in which the channel is broadcast separated by `;`. A list of all supported languages and their codes can be found in [data/languages.csv](data/languages.csv)                                 | Optional | `eng;spa`                     |
 | categories     | List of categories to which this channel belongs separated by `;`. A list of all supported categories can be found in [data/categories.csv](data/categories.csv)                                                 | Optional | `news;weather`                |
-| is_nsfw        | Indicates whether the channel broadcasts adult content (`true` or `false`)                                                                                                                                       | Required | `false`                       |
+| is_nsfw        | Indicates whether the channel broadcasts adult content (`TRUE` or `FALSE`)                                                                                                                                       | Required | `FALSE`                       |
 | logo           | Logo URL                                                                                                                                                                                                         | Optional | `https://example.com/nbc.png` |
 
 ### categories