# 1. Goal
Show the subscriptions of each magazine in an ALV list. The publisher uses the
list to compare the magazines for a period.

# 2. Open questions
None.

# 3. Context
- Table {{P}}SUBS exists in package $TMP. It contains data.
  Fields: SUBS_ID (INT4, key), MAGAZINE (CHAR 12), SUB_STATUS (CHAR 1),
  START_DATE (DATS), MONTHLY_FEE (DEC 15,2).
- SUB_STATUS is 'A' for an active subscription and 'C' for a cancelled
  subscription.

# 4. Contract
- Create the executable program {{P}}SUBS_SUM in package $TMP.
- Selection screen:
  - Parameter P_FROM, type DATS, mandatory: the first start date to include.
  - Select-option S_MAG for the magazine.
- Show the result with CL_SALV_TABLE. The output table has these columns, with
  these names: MAGAZINE, NUM_SUBS (number of included subscriptions),
  REVENUE (sum of MONTHLY_FEE).

# 5. Business rules
1. Include a subscription only if SUB_STATUS is 'A', START_DATE is on or after
   P_FROM, and MAGAZINE is in S_MAG.
2. Show one line for each magazine that has at least two included subscriptions.
3. Sort the lines by REVENUE, the highest revenue first.

# 6. Constraints
- Release target: 7.40 SP05. Use only syntax that this release supports.
- Coding standards: Clean ABAP. Read the data with one database access.
- Out of scope: do not change {{P}}SUBS.

# 7. Acceptance
- The program is active and has no syntax error.
- The hidden tests pass.
- Write ABAP Unit tests as local test classes in the program.