diff --git a/core-functions.md b/core-functions.md
index 731b401..74aa4d3 100644
--- a/core-functions.md
+++ b/core-functions.md
@@ -85,3 +85,7 @@ Public. Takes one argument. Returns that argument, protecting it from evaluation
 
 Public. Takes one argument. If that argument is either an STRG or a READ, parses successive characters from that argument to construct an S-expression in the current environment and returns it.
 
+# (type arg)
+
+Public. Takes one argument. If that argument is readable by the current user, returns a string interned in the *core.types* namespace representing the tag value of the argument, unless the argument is a VECP in which case the value returned represents the tag value of the [[vector space]] object indicated by the VECP.
+