How to use 4GL tracing for ABL clients: WebSpeed Agent (_progres), AppServer Agent (_proapsv) and the 4GL Client (_progres, prowin32, prowin.exe) 
How to enable tracing to diagnose an ABL client's 4GL statements
How to use the -clientlog, -logginglevel and -logentrytypes startup parameters to enable the 4GL tracing feature?
What can be used help troubleshooting issues related to ABL Client statement execution 
What is 4GLTrace logging ?
Where is this ABL statement execution written ?
How to enable ABL Statement logging for WebSpeed Agent or AppServer Agent processes?
How to diagnose isolated ABL code statement execution using a simple ABL GUI (prowin) or CHUI (_progres) client ?

What is 4GLTrace logging ?

The 4GL Tracing Feature is a diagnostic feature that was added in the Progress 9.1D01 Service Pack and improved in later OpenEdge releases. 

In Progress 9.1D01 or higher:

This feature records the execution of the following 4GL statements in a log file:

• RUN
• User-defined FUNCTIONS
• PUBLISH
• SUBSCRIBE

The destination of the messages depends on what the client type is:

• For AppServer and WebSpeed, the messages go to the existing (agent's) server log file.
• For GUI/TTY clients, the log file is the file name specified by the -clientlog startup parameter.
• The -clientlog parameter can also be used without the -logginglevel and -logentrytypes parameters. In this case all error messages and messages that would normally appear in an alert box will still be written to the specified logfile, as well as entries on database connections and disconnections. This information can be used to relate client log messages with database log messages.

4GL Tracing is enabled when the logginglevel parameter is set to 4, and the logentrytypes parameter is set to 2 or higher.  To use -logentrytypes 4 Progress 9.1D09 is required.

In Progress 9.1D01+, 9.1E: To set -logginglevel-logentrytypes parameters:

For GUI/TTY clients, specify the startup parameters -logginglevel 4 -logentrytypes <entrytypes here>

Example:  prowin32.exe -clientlog  mylog.lg -logginglevel 4 -logentrytypes 4GLTrace

For AppServer/WebSpeed, set srvrLoggingLevel to 4 and srvrLogEntries to 2 in the ubroker.properties file.

Example:

  srvrLoggingLevel=4
  srvrLogEntries=2

In OpenEdge 10.x: To set -logginglevel-logentrytypes

Client logging uses a different syntax. 

For GUI/TTY clients
prowin32.exe -clientlog  mylog.lg -logginglevel 2 -logentrytypes 4GLTrace
 
For WebSpeed & AppServer Agents use:

  srvrLoggingLevel=2
  srvrLogEntryTypes=4GLTrace

When configuring UBroker Agents through the OpenEdge Console UI (9090:localhost) the logging level and the log entry types for the agent is set under the Configuration, Logging Setting section. The logginglevel of 2 equates to the Basic setting.

The  current log entry types shows a comma delimited list (no space after each comma). Add a comma and 4GLTRACE as an added entry type:

Example:  ASPlumbing,DB.Connects,4GLTRACE

For further information refer to Article

•  What are the possible values for the -logentrytypes startup parameter in OpenEdge  

For complete information about these logging settings and the resulting ABL trace logging:

Troubleshoot ABL Applications, Log Entry Types Detail
https://docs.progress.com/bundle/openedge-abl-troubleshoot-applications/page/Log-Entry-Types-Detail.html  
 

References to Other Documentation:

Progress Article(s):
 How to use the -weblogerror startup parameter  
 How to troubleshoot a client connection to AIA with an ABL program.  
 How to troubleshoot Progress Application Server for OpenEdge (PASOE)