When a molecular scene contains many objects, a light node can be easy to overlook. That makes small tasks—such as checking which lights are hidden, finding a light by name, or narrowing a search to lights rather than other node types—more fiddly than they need to be.
SAMSON’s Node Specification Language (NSL) provides a focused way to describe light nodes. The light attribute space has the short name li, and it matches only light nodes. That restriction is useful when you want a query to stay focused on scene lighting instead of returning unrelated nodes.
Start with the question you need to answer
For a quick visibility check, the light attributes include visible (short name v) and hidden (short name h). The documented expressions are:
li.vandnot li.vli.handnot li.h
These give you a direct way to express whether the query should match lights with or without the corresponding attribute. For example, if you are auditing a scene and want to focus on lights that are not visible, not li.v is a compact starting point. If you are checking the hidden attribute specifically, use li.h or not li.h instead. Keeping the attribute names explicit helps avoid treating “hidden” and “visible” as interchangeable terms.
Use names to narrow the search
Lights inherit the name attribute from the node attribute space. Its short name is n, and values are written as strings in quotes. The reference includes li.n "A" and li.n "L*" as examples.
This is useful when a scene has several lights and you already know how one is named. Rather than searching visually through the whole scene, you can express the name you are looking for in the light attribute space. The reference shows the exact syntax, including quotation marks; use that format when writing your own name-based expression.
Keep selection attributes distinct
The light attribute space also includes selected, selectionFlag, and visibilityFlag. The documented forms include li.selected, li.sf, li.sf false, li.vf, and li.vf false. Notice that selected has no short name in the light attribute space, while selectionFlag uses sf and visibilityFlag uses vf.
These are separate attributes, so it is worth choosing the one that matches the question you are asking rather than substituting one for another. If you are unsure which attribute your workflow needs, begin with the full name and consult the inherited node-attribute definition for its details.
A practical way to use the reference
- Choose the light-only scope with
li. - Pick the attribute that matches your task: name, visibility, hidden state, selection, or a flag.
- Use the documented short form where available, and include a value such as
falsewhen the example calls for one. - Check the corresponding inherited node attribute if you need more detail about how that attribute is defined.
This keeps a light-node search small and readable, especially when you are troubleshooting a crowded scene or revisiting a project after time away. For the full list of light attributes and their inherited definitions, see the SAMSON light attributes reference.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.