diff --git a/bacnet-stack/bin/readme.txt b/bacnet-stack/bin/readme.txt
index 942c7df6..a3a0dd1f 100644
--- a/bacnet-stack/bin/readme.txt
+++ b/bacnet-stack/bin/readme.txt
@@ -1,23 +1,24 @@
-BACnet Tools are binary demo application command line 
-utilities that use BACnet/IP to perform a variety of 
-BACnet services. Some tools use BACnet WhoIs to bind to 
-devices, but can also use a static binding file address_cache.  
+BACnet Tools are binary demo application command line
+utilities that use BACnet/IP to perform a variety of
+BACnet services. Some tools use BACnet WhoIs to bind to
+devices, but can also use a static binding file address_cache.
 
-Most of the tools have help (--help option), and use 
-environment variables to configure the datalink. 
+Most of the tools have help (--help option), and use
+environment variables to configure the datalink.
 
 The Client Tools use WhoIs to bind to target devices.
 The WhoIs can be eliminated by using the address_cache
 file, which is read by each client tool from the current
-working directory.  Having the device address from the 
-address_cache file will greatly improve the throughput 
-and speed of the client tools. The address_cache file 
+working directory.  Having the device address from the
+address_cache file will greatly improve the throughput
+and speed of the client tools. The address_cache file
 can be generated using the standard output of the bacwi tool.
 
 EXAMPLE:
 bacwi -1 > address_cache
 
-Client Tools:
+Client Tools
+------------
 bacrp - BACnet ReadProperty service
 bacwp - BACnet ReadProperty service
 bacarf - BACnet AtomicReadFile service
@@ -31,18 +32,49 @@ bacts - BACnet TimeSynchronization service
 bacucov - BACnet UnconfirmedChangeOfValue service
 bacrpm - BACnet ReadPropertyMultiple service
 
-Server Tools:
+Server Tools
+------------
 bacserv - BACnet Device Simulator
 
-Router Tools:
+Router Tools
+------------
 baciamr - BACnet I-Am-Router to Network message
 bacinitr - BACnet Initialize Router message
 bacwir - BACnet Who-Is Router to Network message
 
-Capture Tool:
-The mstpcap tool is used for capturing MS/TP traffic 
-from an RS-485 serial adapter and saving the packets 
+MS/TP Capture Tool
+------------------
+The mstpcap tool is used for capturing MS/TP traffic
+from an RS-485 serial adapter and saving the packets
 in a file for viewing by Wireshark.
 
+Environment Variables
+---------------------
+BACNET_APDU_TIMEOUT - set this value in milliseconds to change
+    the APDU timeout.  APDU Timeout is how much time a client
+    waits for a response from a BACnet device. Default is 3000ms.
+
+BACNET_IFACE - set this value to dotted IP address (Windows) of
+    the interface (see ipconfig command on Windows) for which you
+    want to bind.  On Linux, set this to the /dev interface
+    (i.e. eth0, arc0).  Default is eth0 on Linux, and the default
+    interface on Windows.  Hence, if there is only a single network
+    interface on Windows, the applications will choose it, and this
+    setting will not be needed.
+
+BACNET_IP_PORT - UDP/IP port number (0..65534) used for BACnet/IP
+    communications.  Default is 47808 (0xBAC0).
+
+BACNET_BBMD_PORT - UDP/IP port number (0..65534) used for Foreign
+    Device Registration.  Defaults to 47808 (0xBAC0).
+
+BACNET_BBMD_TIMETOLIVE - number of seconds used in Foreign Device
+    Registration (0..65535). Defaults to 60000 seconds.
+
+BACNET_BBMD_ADDRESS - dotted IPv4 address of the BBMD or Foreign Device
+    Registrar.
+
+Source Code
+-----------
 The source code for the BACnet-Tools can be found at:
 http://bacnet.sourceforge.net/
diff --git a/bacnet-stack/demo/handler/dlenv.c b/bacnet-stack/demo/handler/dlenv.c
index b7979e53..af3db6e8 100644
--- a/bacnet-stack/demo/handler/dlenv.c
+++ b/bacnet-stack/demo/handler/dlenv.c
@@ -122,14 +122,26 @@ void dlenv_maintenance_timer(
  * - BACDL_ALL: (the general-purpose solution)
  *   - BACNET_DATALINK to set which BACDL_ type we are using.
  * - (Any):
- *   - BACNET_APDU_TIMEOUT
- *   - BACNET_IFACE
+ *   - BACNET_APDU_TIMEOUT - set this value in milliseconds to change
+ *     the APDU timeout.  APDU Timeout is how much time a client
+ *     waits for a response from a BACnet device.
+ *   - BACNET_IFACE - set this value to dotted IP address (Windows) of
+ *     the interface (see ipconfig command on Windows) for which you
+ *     want to bind.  On Linux, set this to the /dev interface
+ *     (i.e. eth0, arc0).  Default is eth0 on Linux, and the default
+ *     interface on Windows.  Hence, if there is only a single network
+ *     interface on Windows, the applications will choose it, and this
+ *     setting will not be needed.
  * - BACDL_BIP: (BACnet/IP)
- *   - BACNET_IP_PORT
+ *   - BACNET_IP_PORT - UDP/IP port number (0..65534) used for BACnet/IP
+ *     communications.  Default is 47808 (0xBAC0).
  *   - with BBMD_ENABLED also:
- *     - BACNET_BBMD_PORT
- *     - BACNET_BBMD_TIMETOLIVE
- *     - BACNET_BBMD_ADDRESS
+ *     - BACNET_BBMD_PORT - UDP/IP port number (0..65534) used for Foreign
+ *       Device Registration.  Defaults to 47808 (0xBAC0).
+ *     - BACNET_BBMD_TIMETOLIVE - number of seconds used in Foreign Device
+ *       Registration (0..65535). Defaults to 60000 seconds.
+ *     - BACNET_BBMD_ADDRESS - dotted IPv4 address of the BBMD or Foreign
+ *       Device Registrar.
  * - BACDL_MSTP: (BACnet MS/TP)
  *   - BACNET_MAX_INFO_FRAMES
  *   - BACNET_MAX_MASTER