diff --git a/docs/TODO b/docs/TODO
index 2ff601123..fbf64c782 100644
--- a/docs/TODO
+++ b/docs/TODO
@@ -145,7 +145,18 @@
 2.1 More non-blocking
 
  Make sure we don't ever loop because of non-blocking sockets returning
- EWOULDBLOCK or similar. The GnuTLS connection etc.
+ EWOULDBLOCK or similar. Blocking cases include:
+
+ - Name resolves on non-windows unless c-ares is used
+ - GnuTLS SSL connections
+ - NSS SSL connections
+ - Active FTP connections
+ - HTTP proxy CONNECT operations
+ - SOCKS proxy handshakes
+ - file:// transfers
+ - TELNET transfers
+ - The "DONE" operation (post transfer protocol-specific actions) for the
+   protocols SFTP, SMTP, FTP. Fixing Curl_done() for this is a worthy task.
 
 2.2 Remove easy interface internally