Gm
IEC AND dependency (G)
Dependency label Gm: inputs or outputs carrying the number m are ANDed with the affecting G input.
IEC
IEC · Zm
IEC interconnection dependency (Z)
Dependency label Zm showing an internal connection from one point of a symbol to every terminal labelled m.
In plain English
What does IEC interconnection dependency (Z) mean?
Z dependency states that the affecting input or output is internally connected to every input or output labelled with the same number, which then takes its logic state. It lets a symbol show internal wiring without drawing it, for example an internal output that drives several internal inputs.
A simple example
On device symbols, Z dependency often explains why an output appears to have the same state as an internal signal or why a pin also acts on another function. Drafters reproducing such symbols should keep the labels together.
What the drawings help you do
Z dependency indicates logic state transfer only. It does not imply the connection is externally accessible or measurable.
This particular reference
Dependency label Zm showing an internal connection from one point of a symbol to every terminal labelled m. X (transmission) dependency describes a bidirectional switch path controlled by the affecting input; Z is a fixed logical connection.
- Terminal
- An identified point where a conductor connects.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
IEC · Output or internal output labelled Zm with affected terminals labelled m
Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · Zm
What it represents
Z dependency states that the affecting input or output is internally connected to every input or output labelled with the same number, which then takes its logic state. It lets a symbol show internal wiring without drawing it, for example an internal output that drives several internal inputs.
On device symbols, Z dependency often explains why an output appears to have the same state as an internal signal or why a pin also acts on another function. Drafters reproducing such symbols should keep the labels together.
Z dependency indicates logic state transfer only. It does not imply the connection is externally accessible or measurable.
How to read it
- Trace each Zm to every terminal labelled m.
- Z labels describe internal connections, not external wiring.
Information to show or reference
- Label the source as Zm.
- Mark each connected terminal with m.
- Do not use Z labels to stand in for external wiring.
A distinction that matters
X (transmission) dependency describes a bidirectional switch path controlled by the affecting input; Z is a fixed logical connection.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
Z (interconnection) dependency description.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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