To determine the alphanumeric character combination for the vacant space, observe the pattern in the table. The alphanumeric codes are arranged such that each cell contains a combination of a numeric and an alphabetic character. In each row and column, the numeric value seems to follow a specific pattern or arithmetic sequence relating to the other numbers and respective letters in that row or column.

Let's analyze the given rows:

1. **Row1:** Combination of different letters (Y, Z, X) and numeric values increasing by 3 (1, 4, 7).

2. **Row3:** Again, a combination of different letters (Z, Y, X), showcasing a decrement in number by 1 (3, 2, 1).

3. With these two observations, let's deduce the rule for the middle row:

- **Row2:** The first column contains 10Z, third column has 50Y. The number in the middle column should logically follow a similar arithmetic pattern from its surrounding numbers, especially aiming to find the integer close to or exactly averaging numerics in the X column from both others.

Using the column pattern:

The sequence in the X column seems to increment by constant values close to multiples of 10 or simple addition to other numbers seen.

Considering the increments:

- Row1 increment by **3 (1 to 4)**, Row3 consequent decrements by **2 (3 to 1)**. This leads us to assume the second row numeric result to be slightly more direct influence of expectations (other numeric, lesser direct seen).

- Middle space numeric from arithmetic average seems plausible as incrementing linearly (10Z to 50Y) could be an attempt of simplification.

Choose an appropriate pattern across and the suggestion potentializing candidates construction revolving near assumed system link and find desired value:

Thus, within suggested options, 20X is an appropriate fill by systematic decision through understanding viability tested.