When a molecular project contains many conformations, finding the ones relevant to a particular task can become a small but persistent source of friction. A name may not tell you how large a conformation is, and scanning entries one by one is not always the clearest way to narrow a set. In SAMSON, the Node Specification Language (NSL) lets you query path nodes by their number of atoms.
The important detail is that the path attribute space matches only conformation nodes. Its short name is p. To filter paths by atom count, use the numberOfAtoms attribute, abbreviated nat.
Start with a threshold
If you want to find paths containing more than 100 atoms, write:
p.nat > 100
The longer form is path.nat > 100. Both expressions use the same attribute; p is simply the short name for the path attribute space. This kind of threshold is useful when you already have a rough size cutoff in mind and want the query to do the initial narrowing for you.
Search within a size range
If a threshold is too broad, specify a range instead:
p.nat 100:200
This matches paths with a number of atoms between 100 and 200. The full attribute name is path.numberOfAtoms, while p.nat is the compact form. Use the range when you want to focus on a band of path sizes rather than everything above or below a single cutoff.
Keep the attribute straight
NSL attributes can be easy to mix up when several kinds of nodes are involved. Here, nat means the number of atoms in a path; it is not a path name or a selection state. For names, the path attribute space inherits name from the node attribute space, and examples include p.n "A" and p.n "L*". The path space also inherits selected and selectionFlag. These are separate attributes from atom count, so choose the one that expresses the property you actually want to match.
A practical query habit
When writing a query, first identify the node type you mean to match: in this case, conformation nodes in the path space. Next, choose the property—numberOfAtoms—and then express the cutoff or range. Reading a query in that order helps make its intent easier to check: p identifies the space, nat identifies the property, and the remaining part sets the numerical condition.
For example, if your goal is to locate paths above a size threshold, use p.nat > 100. If you want paths within the documented 100–200 interval, use p.nat 100:200. These examples give you a concise way to describe the size criterion instead of relying on names alone.
For the complete attribute reference and additional inherited attributes, see the SAMSON path attributes documentation.
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