To summarize:
substr(STRING,START,LENGTH)

Where:

code:

---

   START > 0 = Start position from start of STRING (1=1st character)
   START < 0 = Start position from end of STRING (-1=Last character, -2=penultimate character)
   LENGTH > 0 = Number of characters to substring
   LENGTH < 0 = Substring end position (-1=Last character in string)

---

Examples:

code:

---

   substr("A String",1,1) = "A"
   substr("A String",3,-1) = "String"
   substr("A String",3,-4) = "Str"
   substr("A String",-3,2) = "in"
   substr("A String",-4,-1) = "ring"
   substr("A String",-6,-4) = "Str"

---

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Richard Howarth