Pattern - String DP

How do you recognize a string DP problem?

$1.$ Comparing two strings? Probably 2D (two-dimensional) DP with $dp[i][j]$.

$2.$ Looking for common structure? Think LCS pattern (match/skip).

$3.$ Converting one string to another? Think Edit Distance pattern (multiple operations).

$4.$ Counting ways? Same structure, but sum instead of max/min. The formula always asks: what happens at position $(i, j)$ based on whether characters match?