Arthashastra
ततो गूढम् एव अपगच्छेत्, स्वजन संज्ञां च प्ररूपयेत् ॥
On such occasions, they should make use of the signs indicative of the purpose of their society.
english translation
tato gUDham eva apagacchet, svajana saMjJAM ca prarUpayet ॥
hk transliteration by Sanscript