I wonder what this STOP is about.

(It's not in response to me because I haven't transmitted in quite a while.)

190445   2  0.3 2512 ~  VE4RK W7YA -04
190500   2  0.3  235 ~  CI1YFZ ND7M DM16
190500  -4  0.2 2381 ~  AE7U AB9BH CN87
190500  11  0.1 1477 ~  K7FR AI9L +07
190515  -2  0.3 2791 ~  STOP
190515   1  0.3 2512 ~  VE4RK W7YA RR73
190530   0  0.3  235 ~  CI1YFZ ND7M DM16
190530  -2  0.2 2382 ~  AE7U AB9BH R+04
190530  17  0.1 1477 ~  K7FR AI9L RR73
190545  -6  0.3 2791 ~  STOP
190600   6  0.2 2381 ~  AE7U AB9BH 73
190615  25  0.3 2512 ~  VE7FM W7YA DM34
190615  -4  0.3 2791 ~  STOP
190630  22  0.2 1477 ~  WB6JJJ AI9L RR73
190630 -18  0.2 1215 ~  KJ5KL N7RO CN88
190645  27  0.3 2512 ~  VE7FM W7YA R-03
190645  -5  0.3 2791 ~  STOP
190700 -17  0.2 1215 ~  KJ5KL N7RO CN88
190700 -21  0.1 1780 ~  K7FR NR5O DM33
190715  25  0.3 2512 ~  VE7FM W7YA 73
190715  -1  0.3 1913 ~  VE7FM ND7M DM16
190715  -4  0.3 2791 ~  STOP