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OpenGL ES 1.0 and EGL 1.0 reference manual and man pages (written by
Claude Knaus, based on OpenGL SI man pages).

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.2//EN" "DTD/docbook/docbookx.dtd">

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  Original Code. The Original Code is: OpenGL ES Reference Manual,
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<refentry id="glGetError">
  <refmeta>
    <refentrytitle>glGetError</refentrytitle>
    <manvolnum>3G</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>glGetError</refname>
    <refpurpose>return error information</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <title>C Specification</title>

    <funcsynopsis>
      <funcprototype>
        <funcdef>GLenum <function>glGetError</function></funcdef>
        <void/>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>
    <function>glGetError</function>
    returns the value of the error flag. Each detectable error is
    assigned a numeric code and symbolic name. When an error
    occurs, the error flag is set to the appropriate error code
    value. No other errors are recorded until 
    <function>glGetError</function>
    is called, the error code is returned, and the flag is reset to
    <constant>GL_NO_ERROR</constant>. If a call to 
    <function>glGetError</function>
    returns <constant>GL_NO_ERROR</constant>,
    there has been no detectable error since the last call to 
    <function>glGetError</function>,
    or since the GL was initialized.</para>

    <para>To allow for distributed implementations, there may be
    several error flags. If any single error flag has recorded an
    error, the value of that flag is returned and that flag is
    reset to <constant>GL_NO_ERROR</constant> when 
    <function>glGetError</function>
    is called. If more than one flag has recorded an error, 
    <function>glGetError</function>
    returns and clears an arbitrary error flag value. Thus, 
    <function>glGetError</function>
    should always be called in a loop, until it returns 
    <constant>GL_NO_ERROR</constant>,
    if all error flags are to be reset.</para>

    <para>Initially, all error flags are set to 
    <constant>GL_NO_ERROR</constant>.</para>

    <para>The following errors are currently defined:</para>

    <variablelist>
      <varlistentry>
        <term>
          <constant>GL_NO_ERROR</constant>
        </term>

        <listitem>
          <para>No error has been recorded. The value of this
          symbolic constant is guaranteed to be 0.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_INVALID_ENUM</constant>
        </term>

        <listitem>
          <para>An unacceptable value is specified for an
          enumerated argument. The offending command is ignored,
          and has no other side effect than to set the error
          flag.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_INVALID_VALUE</constant>
        </term>

        <listitem>
          <para>A numeric argument is out of range. The offending
          command is ignored, and has no other side effect than to
          set the error flag.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_INVALID_OPERATION</constant>
        </term>

        <listitem>
          <para>The specified operation is not allowed in the
          current state. The offending command is ignored, and has
          no other side effect than to set the error flag.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_STACK_OVERFLOW</constant>
        </term>

        <listitem>
          <para>This command would cause a stack overflow. The
          offending command is ignored, and has no other side
          effect than to set the error flag.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_STACK_UNDERFLOW</constant>
        </term>

        <listitem>
          <para>This command would cause a stack underflow. The
          offending command is ignored, and has no other side
          effect than to set the error flag.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_OUT_OF_MEMORY</constant>
        </term>

        <listitem>
          <para>There is not enough memory left to execute the
          command. The state of the GL is undefined, except for the
          state of the error flags, after this error is
          recorded.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>When an error flag is set, results of a GL operation are
    undefined only if <constant>GL_OUT_OF_MEMORY</constant>
    has occurred. In all other cases, the command generating the
    error is ignored and has no effect on the GL state or frame
    buffer contents. If the generating command returns a value, it
    returns 0. If <function>glGetError</function>
    itself generates an error, it returns 0.</para>
  </refsect1>
</refentry>