diff --git a/IQML.m b/IQML.m
index b85cf94..51f0917 100644
--- a/IQML.m
+++ b/IQML.m
@@ -13,7 +13,7 @@
 %        Username        (String)  the login ID for connecting to IQFeed via the client
 %        Password        (String)  the password for connecting to IQFeed via the client
 %
-%     Message processing:
+%     Message processing (also see Logging section below):
 %        Timeout         (Number)  default=5; max # of seconds to wait for a response to a blocking query (0=infinite)
 %        Debug           (Logical) default=0 or false; if true or 1, extra data will be displayed in Matlab console
 %        AddPortStats    (Logical) default=0 or false; if true or 1, extra port stats are streamed and returned when Action=stats
@@ -117,6 +117,12 @@
 %        String          (String)  default=''; command to be sent to IQFeed
 %        PortName        (String)  default='Level1'; one of 'Level1','Level2','Admin'
 %
+%     Logging:
+%        Path            (String)  default=''; Path of folder containing the log file
+%        Details         (Numeric) default=[1,0,0,0,0]; array of flags describing which msg groups to log (Admin,L1,L2,Lookup,Debug)
+%        CopyTo          (String)  default=''; Path of folder or filename to which the live log file is copied
+%        DoThis          (String)  default=''; one of 'show', 'display', 'clear' or 'reset'
+%
 % Refer to the User Guide for detailed documentation and usage examples.
 %
 % THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED
diff --git a/IQML.p b/IQML.p
index e9e8dd4..1018456 100644
Binary files a/IQML.p and b/IQML.p differ
diff --git a/IQML_User_Guide.pdf b/IQML_User_Guide.pdf
index 86619c4..1a59b1a 100644
Binary files a/IQML_User_Guide.pdf and b/IQML_User_Guide.pdf differ
diff --git a/changelog.log b/changelog.log
index 31c469e..aeef102 100644
--- a/changelog.log
+++ b/changelog.log
@@ -1,3 +1,8 @@
+2.15 (2019-03-24)
+  - [9.1]  Fixed a problem with license validation on certain Matlab installations
+  - [12.1] Added display of a few types of IQFeed system messages (excluding stats) in Debug mode
+  - [12.2] Added programmatic control of IQFeed logging
+
 2.14 (2019-03-14)
   - [3.1] Added ability to specify parameters as Matlab class properties (like structs)
   - [3.1] Fixed problem with specifying parameters using a Matlab table