UNIX for Dummies Questions & Answers

Hi guys,
i have a big file with the following format.This includes header(H),detail(D) and trailer(T) information in the file.My problem is i have to search for the character "6h" at 14 th and 15 th position in all the records .if it is there i have to write all those records into a separate file along with the header and trailer and the last nine digits in the trailer should indiacate the count of the detaied records.can any one help me on this how to achive? Basically i am new to unix shell scripting.

following the file format is

HBM6303000000000200805060940412008050609404120080506SCITS 8.2
D6303200805066HJ8164-61002 EURO6303I0073554514 0017992008031120080430HP00DD00Hewlett-Packard Pte Ltd 12.000 20080502 0000000509.3900UDNB USDEA 00001EA SG 00022797990001 00000120080226 0073554514 6303 N101 HP00DD00 20080503 00022797990001
D6303200805066HJ8164-61002 EURO6303I0073554514 0018052008031120080430HP00DD00Hewlett-Packard Pte Ltd 16.000 20080502 0000000509.3900UDNB USDEA 00001EA SG 00022798050001 00000120080226 0073554514 6303 N101 HP00DD00 20080503 00022798050001
D6303200805066HJ8164-61002 EURO6303I0073554514 0018142008031120080430HP00DD00Hewlett-Packard Pte Ltd 16.000 20080502 0000000509.3900UDNB USDEA 00001EA SG 00022798140001 00000120080226 0073554514 6303 N101 HP00DD00 20080503 00022798140001
D6303200805066HJ8164-61002 EURO6303I0073554514 0018092008031120080430HP00DD00Hewlett-Packard Pte Ltd 16.000 20080502 0000000509.3900UDNB USDEA 00001EA SG 00022798090001 00000120080226 0073554514 6303 N101 HP00DD00 20080503 00022798090001
TBM630300000000020080506094041000003818

advancedthanks
narasimha.

Code:

awk '/^H/ { h=$0; next }
/^T/ { if (p) print; p=0; next }
substr($0,14,2) == "6h" { if (h) print h; if (d) print d; print; h = d = ""; p=1; next }
{ h = d = ""; p=0; }' file

With only a single example to test with, it's hard to know if this correct. Apparently all the D lines in an entry will have "6H" (not "6h")?