<div>
  Environment variables defined here will be made available to every build
  executed by this agent, and will override any environment variables that have
  the same <i>Name</i> as those defined on the <i>Configure System</i> page.
  <p>
  Using the syntax <code>$NAME</code> or <code>${NAME}</code>
  (<code>%NAME%</code> on Windows), these variables can be used in job
  configurations, or from process launched by a build.
  <p>
  Jenkins also supports a special syntax, <code>BASE+EXTRA</code>, which allows
  you to add multiple key-value pairs here, which will be prepended to an
  existing environment variable.
  <p>
  For example, if you have a machine which has <code>PATH=/usr/bin</code>, you
  could add to the standard path by defining an environment variable here, with
  the name <code>PATH+LOCAL_BIN</code> and value <code>/usr/local/bin</code>.
  <br>
  This would result in <code>PATH=/usr/local/bin:/usr/bin</code> being exported
  during builds executed on this machine.
  <code>PATH+LOCAL_BIN=/usr/local/bin</code> will also be exported.
  <br>
  Multiple entries are prepended to the "base" variable according to the
  alphabetical order of the "extra" part  of the name.
  <p>
  If the <i>Value</i> is empty or whitespace-only, it will not be added to the
  environment.
</div>

<div>
  Environment variables defined here will be made available to every build
  executed by this agent, and will override any environment variables that have
  the same <i>Name</i> as those defined on the <i>Configure System</i> page.
  <p>
  Using the syntax <code>$NAME</code> or <code>${NAME}</code>
  (<code>%NAME%</code> on Windows), these variables can be used in job
  configurations, or from process launched by a build.
  <p>
  Jenkins also supports a special syntax, <code>BASE+EXTRA</code>, which allows
  you to add multiple key-value pairs here, which will be prepended to an
  existing environment variable.
  <p>
  For example, if you have a machine which has <code>PATH=/usr/bin</code>, you
  could add to the standard path by defining an environment variable here, with
  the name <code>PATH+LOCAL_BIN</code> and value <code>/usr/local/bin</code>.
  <br>
  This would result in <code>PATH=/usr/local/bin:/usr/bin</code> being exported
  during builds executed on this machine.
  <code>PATH+LOCAL_BIN=/usr/local/bin</code> will also be exported.
  <br>
  Multiple entries are prepended to the "base" variable according to the
  alphabetical order of the "extra" part  of the name.
  <p>
  If the <i>Value</i> is empty or whitespace-only, it will not be added to the
  environment, nor will it override or unset any environment variable with the
  same name that may already exist (e.g. a variable defined by the system).
</div>

Add note about empty environment variables not overriding existing ones.
Add note about empty environment variables not overriding existing ones.
