Marking/labeling node-edge connection points with graphviz - layout

Question

With Graphviz, I know I can label edges and vertices. But what if I want to label some of the connections? That is, label some points where a specific edge meets a specific vertex? Is that possible?
Notes:
I don't care about beatuy/visual styles, I'll take something plain and dirty(ish)
I would very much rather not use "tricks" such as spacing out the vertex label to make some of the text appear next to the connection points and similar approaches.

Answer 1

You can use the taillabel and headlabel edges attributes. For example:
digraph G {
rankdir="LR";
a->b [taillabel="from"; headlabel="to"]
b->c [taillabel="from"; headlabel="to"]
}
produce:

Answer 2

A clear way to label where something is leaving or coming into a node is to use "port"-like constructs inside the source/target nodes. Some ways to achieve this:
subgraph.dot
digraph {
subgraph cluster_house {
label="House"
hcw [label="Clean water"]
hdw [label="Dirty water"]
}
subgraph cluster_street {
label="Street"
scw [label="Clean water"]
sdw [label="Dirty water"]
}
scw -> hcw
hdw -> sdw
}
Docs: https://graphviz.org/docs/attrs/cluster/
struct.dot
digraph structs {
node [shape=record];
rankdir=LR
house [label="<l> House|<cw> Clean water|<dw> Dirty water"];
street [label="<l> Street|<cw> Clean water|<dw> Dirty water"];
street:cw -> house:cw;
house:dw -> street:dw;
}
Docs: https://graphviz.org/doc/info/shapes.html#record
I don't know how to make the headers stand out however with this approach: graphviz: record node with a bold title
html.dot
digraph structs {
node [shape=plaintext]
house [label=<
<table border="0" cellborder="1" cellspacing="0">
<th><td><b>House</b></td></th>
<tr><td port="cw">Clean water</td></tr>
<tr><td port="dw">Dirty water</td></tr>
</table>>];
street [label=<
<table border="0" cellborder="1" cellspacing="0">
<th><td><b>Street</b></td></th>
<tr><td port="cw">Clean water</td></tr>
<tr><td port="dw">Dirty water</td></tr>
</table>>];
street:cw -> house:cw;
house:dw -> street:dw;
}
Docs: https://graphviz.org/doc/info/shapes.html#html
Tested on Graphviz 2.42.2, Ubuntu 22.04.