How Discoverer decodes the EXP_FORMULA1 in eul5_expressions table?

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1. In one of the folders, I have defined an item using a functions like

STDDEV(4) KEEP(DENSE_RANK FIRST ORDER BY  Invoice_Id ) OVER(PARTITION BY Invoice_Num )

2. This expression is stored in table EUL5_EXPRESSIONS in EXP_FORMULA1 column as

[1,225]([1,243]([5,2,"4"]),[1,226]([1,227](),[1,139]([1,140]([6,302815]))),[1,252]([1,138]([6,302816])))

3. When I decode this, I get the output

KEEP(STDDEV2(4),KEEPCOMPONENT(DENSERANKFIRST(),ORDER(NPASSORDERCOMP(INVOICE_ID))),OVER(PARTIION(INVOICE_NUM)))

which is not exactly what I have defined in point1. Is there anyway to decode point2 to get what's there in point1. How Discoverer decodes it?