function masque_div()
{
window.document.getElementById('default_text').style.visibility ='visible';
window.document.getElementById('boulogne_text').style.visibility ='hidden';
window.document.getElementById('calais_text').style.visibility ='hidden';
window.document.getElementById('stomer_text').style.visibility ='hidden';
window.document.getElementById('bethune_text').style.visibility ='hidden';
window.document.getElementById('arras_text').style.visibility ='hidden';
window.document.getElementById('lens_text').style.visibility ='hidden';
window.document.getElementById('dunkerque_text').style.visibility ='hidden';
window.document.getElementById('hazebrouck_text').style.visibility ='hidden';
window.document.getElementById('lillecentre_text').style.visibility ='hidden';
window.document.getElementById('lillenord_text').style.visibility ='hidden';
window.document.getElementById('lillesud_text').style.visibility ='hidden';
window.document.getElementById('valenciennes_text').style.visibility ='hidden';
window.document.getElementById('cambrai_text').style.visibility ='hidden';
window.document.getElementById('avesnes_text').style.visibility ='hidden';
}

function affichage_div(reseau)
{
masque_div();
window.document.getElementById('default_text').style.visibility ='hidden';
window.document.getElementById(reseau).style.visibility ='visible';
}