WordPress at a glance
function is not described

IXR_Server::setCapabilities() public WP 1.0

It's a method of the class: IXR_Server{}

No Hooks.

Return

Null. Nothing.

Usage

$IXR_Server = new IXR_Server();
$IXR_Server->setCapabilities();

Code of IXR_Server::setCapabilities() WP 5.5.1

<?php
function setCapabilities()
{
    // Initialises capabilities array
    $this->capabilities = array(
        'xmlrpc' => array(
            'specUrl' => 'http://www.xmlrpc.com/spec',
            'specVersion' => 1
    ),
        'faults_interop' => array(
            'specUrl' => 'http://xmlrpc-epi.sourceforge.net/specs/rfc.fault_codes.php',
            'specVersion' => 20010516
    ),
        'system.multicall' => array(
            'specUrl' => 'http://www.xmlrpc.com/discuss/msgReader$1208',
            'specVersion' => 1
    ),
    );
}