- 1.7
- 1.6
- 1.5
- Beta
- Examples (for 1.6a)
- Misc
This section lists all the available commands that may make up a type description. Many keywords only make sense within the bracketed parts of keywords that expand the depth of the description. For instance, it is meaningless to specify the connection type with the 'bond' keyword in the root of a typing command since no connections are relevant at this point.
Specifies that a connection to 'X' must exist, but makes no demand of the type (bond order) of the connection. 'X' may be either an element symbol, an id for another type specifier, or a list containing one or both of these to allow more flexible specifications. Specifying an 'unknown' connection with ~X is often useful in, for example, aromatic rings or conjugated systems where the connection might be either a double or single bond.
For example:
Table 8.2. NETA keyword '~X' examples
| Command | Meaning |
|---|---|
| ~C | Any bond to a carbon atom |
| ~&101 | Any bond to an atom which matches type ID 101 (see reusing rypes) |
| ~[N,S,P] | Any connection to either nitrogen, sulfur, or phosphorous |
| !=O | Any bond to any atom, as long as its not a double bond to an oxygen |