The Collaborative International Dictionary of English v.0.48:

Sigla \Sig"la\, n. pl. [L.]
   The signs, abbreviations, letters, or characters standing for
   words, shorthand, etc., in ancient manuscripts, or on coins,
   medals, etc. --W. Savage.
   [1913 Webster]

The Free On-line Dictionary of Computing (30 December 2018):

SIGLA

    SIGma LAnguage.  A language for industrial robots
   from Olivetti.

   ["SIGLA: The Olivetti Sigma Robot Programming Language",
   M. Salmon, Proc 8th Intl Symp on Industrial Robots, 1978,
   pp. 358-363].