diff --git a/RETRO-Book.md b/RETRO-Book.md
index 2217810..9084a77 100644
--- a/RETRO-Book.md
+++ b/RETRO-Book.md
@@ -507,6 +507,8 @@ Word names in RETRO generally follow the following conventions.
 * Don't use a prefix as the first character of a name
 * Don't use underscores in word names
 * Use short names for indices
+* Word names start with a `-` for "not"
+* Words returning a flag end in ?
 
 ## Typical Format
 
diff --git a/doc/book/Programming-Techniques-Naming-Conventions b/doc/book/Programming-Techniques-Naming-Conventions
index deb2217..8402294 100644
--- a/doc/book/Programming-Techniques-Naming-Conventions
+++ b/doc/book/Programming-Techniques-Naming-Conventions
@@ -9,6 +9,8 @@ Word names in RETRO generally follow the following conventions.
 * Don't use a prefix as the first character of a name
 * Don't use underscores in word names
 * Use short names for indices
+* Word names start with a `-` for "not"
+* Words returning a flag end in ?
 
 ## Typical Format