@chris.c.zhao chris.c.zhao Thanks for your patience on this. I have checked with internal team and they has confirmed that nn means normalizednumber.
A tangible example of this would be numbers with formatting characters. Both the original value and "nn" version are stored as tokens. For example, 1,200 becomes the following tokens:
"tokens": [
{
"token": "1,200",
"startOffset": 0,
"endOffset": 5,
"position": 0
},
{
"token": "nn1200",
"startOffset": 0,
"endOffset": 5,
"position": 0
}
]