"NI" is used for numerical intervals or ranges, with "NIf" and "NIt" used to
denote the lower and upper bounds of the range:

                           +-----ND----+
                    +-NIfn-+-NItn-+    |
                    |      |      |    |
          It takes  2      -      3 times the effort .
          It takes  2     to      3 times the effort .

NI*n is used to connect to numbers, while NI*u connects to units
(in this example, kiloDaltons):

                              +--NItu--+
                    +-ND+-NIfu+    +-ND+
                    |   |     |    |   |
     A fragment of 15  kDa   to   20  kDa was obtained.

NI*p is used only for DNA ends:

                               +-----MVp----+      
                               |       +NIfp+-NItp+
                               |       |    |     |
    these transcripts are located.v-d 5' to.j-ru 3' 


The center of the range connects all the words together, and is then
used to connect to the outside world - that is, the center connects
in the same way that an ordinary number might.

NIr is used to connect a word starting the range:

             +------O-----+
             |     +--NIr-+----M--+
             |     |  +NIf+NItn+  |
             |     |  |   |    |  |
     There are.v from 5   to  20 of them .

              +---NIr---+-----D---+
              |    +NIfn+NItn+    |
              |    |    |    |    |
    I have between 5   and  20   dogs
    *I have between dogs and cats


NIc is used in a few special idiomatic number phrases:

           +-----O------+
           |      +-NIc-+
           |      |     |
        Take.v another 12

See also "NM" for a related
numerical-modifier usage.

"NIm" and "NIn" are used in money amounts: "It is a two cent needle",
"that's a one dollar cigar".

NIa is used in ordered lists:

               +-------MVa------+
     +NIa+--Wi-+---Os---+       |
     |   |     |        |       |
     B  :.j press.v button.n firmly 


See also the conjunction overview.