SAP Transaction and Their Structure

In SAP, list of transaction codes are present in table TSTC. The list with a description of the transaction codes is in table TSTCT. If you want to check data present in that table than you have to run Transaction Code as SE16.

Search for a Transaction in SAP
To search for a transaction code use Transaction : SDMO
This search is not case sensitive in its search criteria so it is much easier to use than searching the table.

Command Line
The command line is the white box on the upper left of the screen where you may type transaction codes.
In the SAP command line, if you want to use a transaction, type , for example MR00. If you are using any Transaction than you will use “\n” to go to Easy Access Screen or use back Key or Use Shift+F3.
If you want to go to the transaction but in a new window of SAP, type /o before the transaction as Prefix. If you just want a new window of SAP, type /o in the command line. Remember one thing the maximum screen we can open is 6.
To end a session, in the command line type /I.
The command line has a drop down box. If you click on the drop down arrow on the command line you will see a list of the last few transaction codes that you have keyed in the command line. The list does not contain transaction codes that you have executed via menu paths, or the IMG. Maximum Transaction List is 15.

Dynamic Menu
From the screen at the main menu in R/3, there is a DYNAMIC MENU button. The DYNAMIC MENU is a hierarchy listing of the menu paths in R/3. If you click on the DYNAMIC MENU button and expand the nodes below it, the transaction codes are listed next to the menu path node. You will find all the TCODES of SAP.

Determining a Transaction Code
To find the transaction code for the process you are in at the time in R/3, go to SYSTEM -> STATUS from the menu and in the pop-up screen, the transaction code will be listed or lower right corner there is a list, in that list you can select Transaction.
Naming Standards
SAP loosely uses standards when assigning numbers and letters to create a transaction code. These standards are followed mostly for functional transactions and not for configuration transactions. These standards are not always followed. This is a guideline of how the standards usually work, to give you a starting point on how transaction codes are organized.
A transaction that ends in the number below usually has the function of
00 = main menu, 1 = ADD, 2 = MODIFY, 3 = DISPLAY
If a transaction ends in a number, it may perform the function as listed to the left. For example:
MIRO –To enter incoming invoice referencing a PO
MIR4 –Display Invoice Document
MIR5 –Display List of Invoice Documents
VA00 –Sales Order Main Menu
VA01 –Sales Order Creation
VA02 - Change Sales Order
ME21N –Purchase Order Creation
ME22N –Change Purchase Order
ME23N –Display Purchase Order
XK01 –Create Vendor
XD01 –Create Customer
FS01 –Create General Ledger Account

Transactions beginning in are these types of transactions:
F – Financial
FK – Financial Vendor Master
FS – Ledger Accounts
FB – Shared Financial Transactions (Shared between AP AR Assets GL)
M – Material Management
MK – Material Vendor Master
MB – Goods Receipt – Inventory Management
MR – MM Invoice Verification
ME – Purchasing
ME2 – Purchase Order
MM – Material Master
V – Sales and Distribution
VA – Sales Order
VF – Billing
XK – Central Vendor Master
XD – Central Customer Master
O – Usually configuration Transactions (Config transactions begin with various letters)
Within transactions the following letters have meaning. These letters also refer to General Ledger account types and are used in naming system tables.
A – Assets (first letter fo the German word Anlagengegenstand)
D – Customer/ debit type transactions (first letter of German word Debitor)
K – Vendor/credit type of transactions (first letter of German word Kredit)
M – Material (first letter of German word Material)
S – Ledger (first letter of the German word Soll)
Examples of D, K, M, and S used in transactions – fill # in with D, K, M, or S.
F#01 – CREATE FINANCIAL CUSTOMER, VENDOR, OR LEDGER,
The F at the beginning denotes a financial transaction,
The 1 at the end denotes CREATE.
FD01 is create financial level customer accounts.
FK01 is create financial level vendor accounts
FS01 is create financial ledger accounts.