How to tag the paragraph indent level using c#

Question

Sorry guys, i was in hurry, so i coudlnt  explain fully,

i want to tag the " book index" like

the " book index" like

-----------------------------------------------------------------------------------------------------------
INDEX
AC (Advance Audio Coding), 5, 15
Automated Self-Optimization of Cellular Networks, 144
Automatic frequency planning. See AFP
Automatic neighbor relation. See ANR

Backup service coverage, 193–4, 196
BAL (BCCH Allocation List), 114, 213
Balancing, 23, 25, 43, 115, 156, 169, 173, 175, 184, 186–91, 217

 techniques, 188, 250, 255

 differential, 233–4, 236, 243, 248, 251

 procedure, 76, 177–8

 requests, 171–2

Band, 11–13, 99, 191–3, 213
Bandwidth, 8, 13, 81, 94, 97–8, 100, 181–2
------------------------------------------------------------------------------------------
i just want to find the indent level using c# coding, also i want tag the index like this

<indexEntryGroup>
 <indexEntry>AC (Advance Audio Coding), 5, 15 </indexEntry>
 <indexEntry>Automatic frequency planning. See AFP</indexEntry>
 <indexEntry>Automatic frequency planning. See AFP </indexEntry>
 </indexEntryGroup>

<indexEntryGroup>
 <indexEntry >Backup service coverage, 193–4, 196 </indexEntry>
 <indexEntry >BAL (BCCH Allocation List), 114, 213</indexEntry>
 <indexEntryGroup>

 <indexEntry > techniques, 188, 250, 255</indexEntry>

 <indexEntryGroup>

 <indexEntry > differential, 233–4, 236, 243, 248, 251</indexEntry>

 <indexEntry > procedure, 76, 177–8</indexEntry>

 <indexEntry > requests, 171–2</indexEntry>

 </indexEntryGroup>
 </indexEntryGroup>
 <indexEntry >Band, 11–13, 99, 191–3, 213 </indexEntry>
 <indexEntry >Bandwidth, 8, 13, 81, 94, 97–8, 100, 181–2 </indexEntry>
 </indexEntryGroup>




the first grouping end with enter mark. i want group the index using their indent level, pleaseguide me to do this  process please