We have a lot of terminal numbers (3, 4, 5 … 12, 18) “signals between terminals are normally electrical (or pneumatic …)

2. Wire the jumper on the M-2025 Interface Module to the proper position: between terminals 4 and 5 for Bipolar (-1 to +1 milliamp) signal; between terminals 5 and 6 for Unipolar (0 to 1 milliamp, 0 to 2 milliamp, and 4 to 20 milliamp) signal
http://www.incon.com/documents/incon/pdf/0002060b_appbulleti...

To close the door, the train control sends a low signal (zero voltage) between terminals 8 and 11 (FIG. 1). A low signal between terminals 8 and 11 (FIG. 1) will cause the output of CR2 (FIG. 1) to switch from the door open line to the door close line.
http://www.google.com.ar/patents/US5134350

The product must be installed with the earthconnected, using the special yellow-green terminal on the terminal block. Do not use the neutral for the earth connection.
Le produit doit être installé avec la connexion terre branchée, en utilisant la signalisation et les bornes spécifiques (jaune/vert) à la mise à la terre. Ne pas utiliser le neutre comme mise à la terre
:
S2:Turn ON the MC humidifier and check that:
a) power supply between terminals 3 and 5 (6 and 8 in duct models) is correct (+24Vdc);
b) the probe signal between terminals 3 and 4 (6 and 7 in duct models) ranges between 0
and 1Vdc;
ftp://79.120.55.226/Carel/Manuals/mc/030221740.pdf

2.
The oscillator circuit according to claim 1, characterized in that the even numbered delay cells (7, S1) are coupled to a first common supply voltage terminal (8), whereas the odd numbered delay cells (7, S2) are coupled to a further common supply voltage terminal
:
2.
Circuit oscillateur selon la revendication 1, caractérisé en ce que les cellules de retards de numéros pairs (7, S1)sont couplées à une première borne de tension d’alimentation commune (8), alors que les cellules de retard de numéros impairs (7, S2) sont couplées à une autre borne de tension d’alimentation commune.
https://data.epo.org/publication-server/pdf-document/EP00931...

Area Circuit theory / General
IEV ref 131-11-11
en
terminal
point of interconnection of an electric circuit element, an electric circuit or a network with other electric circuit elements, electric circuits or networks

Note 1 – For an electric circuit element the terminals are the points at which or between which the related integral quantities are defined. At each terminal, there is only one electric current from outside into the element.
Note 2 – The term "terminal" has a related meaning in IEC 60050-151.
fr
borne, f
point de connexion d'un élément de circuit électrique, d'un circuit électrique ou d'un réseau à d'autres éléments de circuit électriques, circuits électriques ou réseaux
Note 1 – Pour un élément de circuit électrique, les bornes sont les points auxquels ou entre lesquels les grandeurs intégrales sont définies. À chaque borne, il y a un seul courant électrique de l'extérieur vers l'élément de circuit.
Note 2 – Le terme "borne" a un sens apparenté dans la CEI 60050-151.
http://www.electropedia.org/iev/iev.nsf/display?openform&iev...


--------------------------------------------------
Note added at 19 hrs (2015-03-07 17:12:52 GMT)
--------------------------------------------------

The full text reads as follows:

Motorised gate for pedestrian access control.
The system consists of a pedestal or column, from the side of which extends a tubular barrier that closes off access and operates in only one direction, i.e. single-directional. The barrier normally remains closed and it opens when it receives an signal from a remote pushbutton. Once access has taken place, it closes again through a timer action.
A normally open and free of voltage contact when tilting in close with a duration between 150 and 500 msec. Between terminals 12 and 18, the door wing starts moving to one side, allowing free entrance. When receiving an impulse of the same characteristics between 12 and 17, the door wing will return to its central position again blocking the entrance. If this last impulse is not given within the given time on the potentiometer P1, the door wing will automatically return to its position blocking the pass.
If the door wing is blocked in its way and cannot complete its path in the programmed time (set up in the factory), the system will stop during a moment and try again to complete the action, repeating this cycle continuously. While the shutdown lasts, the system provides an intermittent signal between terminals 3, 4 and 5, which correspond to the three voltage-free contacts in a relay.
http://www....Manual_ (Link hidden) in order not to compromise the asker.

Every expert in electricity can easily deduct from the text, that electrical terminals are referred.