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What do the official WHO and CDC growth curves actually say, month by month?

Quick answer

What do the official WHO and CDC growth curves actually say, month by month?

They say it in three numbers per age. Both agencies publish their curves as LMS parameters, L for skew, M for the median, and S for spread, and every percentile on every growth chart is solved from those three. This page publishes all 374 rows this site loads, with the source file and retrieval date for each, plus the percentile values computed from them.

Last reviewed 2026-08-28 by Babypercentiles editorial team

How this was collected

Every parameter table on this page was downloaded from the publishing agency's own site: the WHO Child Growth Standards tables from who.int, and the CDC 2000 Growth Charts data file from cdc.gov. The L, M and S values are reproduced exactly as published, with no rounding, smoothing, or re-fitting, and every percentile shown is computed from them here at build time rather than copied from any third party's compiled table. Nothing is included unless it came from the agency file itself, which is why nothing on this page is attributed to a secondary source.

Newest file in this dataset retrieved .

What the data shows

LMS rows published on this page

374

across five agency tables, both sexes

WHO 50th percentile weight, boys, 12 months

9.65 kg

21.3 lb

WHO 50th percentile weight, girls, 12 months

8.95 kg

19.7 lb

Weight step at the 24-month seam, boys

0.52 kg

WHO 12.15 kg to CDC 12.67 kg

Length step at the 24-month seam, boys

1.36 cm

WHO length 87.82 cm to CDC stature 86.45 cm

Middle half of the reference population, boys, 12 months

1.42 kg

25th to 75th percentile weight

The last two figures are the ones people find most surprising. The middle half of the whole reference population of 12 month old boys fits inside 1.42 kg, so a large share of percentile rank turns on a small amount of weight. And the curve is not symmetric: the 3rd to 10th percentile band spans 0.54 kg while the identically-wide 90th to 97th band spans 0.74 kg, because there is more room to be heavy than to be light.

Computed percentile values at the ages people ask about

Each cell is solved from the published L, M and S at that age, using the reference this site applies at that age: WHO through 24 months and the CDC 2000 charts from 24 months, except head circumference, which stays on WHO throughout.

Weight for age

Weight for age, the curve most parents are shown first.

Weight for age: 3rd, 50th and 97th percentile values in kg, computed from the published LMS parameters
Age Reference Boys 3rd Boys 50th Boys 97th Girls 3rd Girls 50th Girls 97th
0 mo WHO 2.513.354.35 2.443.234.17
2 mo WHO 4.395.576.99 4.005.136.53
4 mo WHO 5.647.008.63 5.096.428.11
6 mo WHO 6.447.939.72 5.817.309.20
9 mo WHO 7.248.9010.90 6.568.2310.39
12 mo WHO 7.859.6511.83 7.148.9511.33
18 mo WHO 8.8710.9413.48 8.1710.2312.99
24 mo CDC 10.3812.6715.60 9.9912.0615.00
36 mo CDC 11.7614.3317.94 11.3313.8717.87
48 mo CDC 13.2316.2320.87 12.7115.7921.14
60 mo CDC 14.7918.3924.31 14.2717.9324.79

Source: WHO Child Growth Standards (2006), weight-for-age retrieved 2026-08-28 and CDC 2000 Growth Charts, weight-for-age (2 to 20 years) retrieved 2026-08-28 . For reference, the 50th percentile weight for boys at 12 months is 9.65 kg, or 21.3 lb.

Length or height for age

Measured lying down (length) under 24 months and standing (height) from 24 months, which is also where the reference table changes.

Length or height for age: 3rd, 50th and 97th percentile values in cm, computed from the published LMS parameters
Age Reference Boys 3rd Boys 50th Boys 97th Girls 3rd Girls 50th Girls 97th
0 mo WHO 46.3249.8853.44 45.6449.1552.65
2 mo WHO 54.6658.4262.19 53.2457.0760.90
4 mo WHO 59.9763.8967.80 58.0262.0966.16
6 mo WHO 63.6067.6271.65 61.4765.7369.99
9 mo WHO 67.7571.9776.19 65.6070.1474.69
12 mo WHO 71.2875.7580.22 69.1774.0278.86
18 mo WHO 77.1982.2687.33 75.2580.7186.17
24 mo CDC 79.9186.4593.02 78.4484.9891.48
36 mo CDC 88.0794.96102.60 86.6393.92101.47
48 mo CDC 94.35102.22110.23 92.81100.75109.20
60 mo CDC 100.09108.90117.53 99.08107.66117.02

Source: WHO Child Growth Standards (2006), length-for-age (recumbent length, 0 to 24 months) retrieved 2026-08-28 and CDC 2000 Growth Charts, stature-for-age (2 to 20 years) retrieved 2026-08-28 . For reference, the 50th percentile weight for boys at 12 months is 9.65 kg, or 21.3 lb.

Head circumference for age

Measured around the widest part of the head. This one stays on the WHO standard the whole way.

Head circumference for age: 3rd, 50th and 97th percentile values in cm, computed from the published LMS parameters
Age Reference Boys 3rd Boys 50th Boys 97th Girls 3rd Girls 50th Girls 97th
0 mo WHO 32.0734.4636.85 31.6533.8836.11
2 mo WHO 36.9239.1341.33 35.9738.2540.53
4 mo WHO 39.3941.6343.88 38.2040.5842.96
6 mo WHO 41.0343.3345.63 39.7542.2044.65
9 mo WHO 42.6445.0047.36 41.3143.8346.35
12 mo WHO 43.6546.0748.48 42.3444.9047.45
18 mo WHO 44.8847.3749.87 43.6446.2448.84
24 mo WHO 45.6948.2550.81 44.5647.1849.81
36 mo WHO 46.7949.4652.13 45.8548.5151.17
48 mo WHO 47.4650.2152.96 46.6649.3352.00
60 mo WHO 47.9350.7453.55 47.2549.9252.60

Source: WHO Child Growth Standards (2007 head circumference release), head-circumference-for-age retrieved 2026-08-28 . For reference, the 50th percentile weight for boys at 12 months is 9.65 kg, or 21.3 lb.

The full parameter tables

These are the tables everything else on this site is computed from, reproduced exactly as published. If you want to check a percentile by hand, run z = ((X / M) ^ L minus 1) / (L x S) against the row for your age and read the result through a standard normal distribution.

WHO: Weight for age

WHO percentile tables published by the World Health Organization; the L, M and S columns are reproduced exactly as published. Trimmed at 24 months because this site switches to the CDC 2000 reference at exactly 24 months for weight and stature. Granularity: one row per completed month of age, 0 through 24 months

WHO Child Growth Standards (2006), weight-for-age, published L, M and S values in kg. Source file https://www.who.int/tools/child-growth-standards/standards/weight-for-age, verified 2026-08-28
Age (months) Boys L Boys M Boys S Girls L Girls M Girls S
0 0.3487 3.3464 0.14602 0.3809 3.2322 0.14171
1 0.2297 4.4709 0.13395 0.1714 4.1873 0.13724
2 0.197 5.5675 0.12385 0.0962 5.1282 0.13
3 0.1738 6.3762 0.11727 0.0402 5.8458 0.12619
4 0.1553 7.0023 0.11316 -0.005 6.4237 0.12402
5 0.1395 7.5105 0.1108 -0.043 6.8985 0.12274
6 0.1257 7.934 0.10958 -0.0756 7.297 0.12204
7 0.1134 8.297 0.10902 -0.1039 7.6422 0.12178
8 0.1021 8.6151 0.10882 -0.1288 7.9487 0.12181
9 0.0917 8.9014 0.10881 -0.1507 8.2254 0.12199
10 0.082 9.1649 0.10891 -0.17 8.48 0.12223
11 0.073 9.4122 0.10906 -0.1872 8.7192 0.12247
12 0.0644 9.6479 0.10925 -0.2024 8.9481 0.12268
13 0.0563 9.8749 0.10949 -0.2158 9.1699 0.12283
14 0.0487 10.0953 0.10976 -0.2278 9.387 0.12294
15 0.0413 10.3108 0.11007 -0.2384 9.6008 0.12299
16 0.0343 10.5228 0.11041 -0.2478 9.8124 0.12303
17 0.0275 10.7319 0.11079 -0.2562 10.0226 0.12306
18 0.0211 10.9385 0.11119 -0.2637 10.2315 0.12309
19 0.0148 11.143 0.11164 -0.2703 10.4393 0.12315
20 0.0087 11.3462 0.11211 -0.2762 10.6464 0.12323
21 0.0029 11.5486 0.11261 -0.2815 10.8534 0.12335
22 -0.0028 11.7504 0.11314 -0.2862 11.0608 0.1235
23 -0.0083 11.9514 0.11369 -0.2903 11.2688 0.12369
24 -0.0137 12.1515 0.11426 -0.2941 11.4775 0.1239

WHO: Length or height for age

Recumbent length. WHO publishes a separate standing-height table from 24 months; this site switches to the CDC 2000 stature reference at exactly 24 months instead. Granularity: one row per completed month of age, 0 through 24 months

WHO Child Growth Standards (2006), length-for-age (recumbent length, 0 to 24 months), published L, M and S values in cm. Source file https://www.who.int/tools/child-growth-standards/standards/length-height-for-age, verified 2026-08-28
Age (months) Boys L Boys M Boys S Girls L Girls M Girls S
0 1 49.8842 0.03795 1 49.1477 0.0379
1 1 54.7244 0.03557 1 53.6872 0.0364
2 1 58.4249 0.03424 1 57.0673 0.03568
3 1 61.4292 0.03328 1 59.8029 0.0352
4 1 63.886 0.03257 1 62.0899 0.03486
5 1 65.9026 0.03204 1 64.0301 0.03463
6 1 67.6236 0.03165 1 65.7311 0.03448
7 1 69.1645 0.03139 1 67.2873 0.03441
8 1 70.5994 0.03124 1 68.7498 0.0344
9 1 71.9687 0.03117 1 70.1435 0.03444
10 1 73.2812 0.03118 1 71.4818 0.03452
11 1 74.5388 0.03125 1 72.771 0.03464
12 1 75.7488 0.03137 1 74.015 0.03479
13 1 76.9186 0.03154 1 75.2176 0.03496
14 1 78.0497 0.03174 1 76.3817 0.03514
15 1 79.1458 0.03197 1 77.5099 0.03534
16 1 80.2113 0.03222 1 78.6055 0.03555
17 1 81.2487 0.0325 1 79.671 0.03576
18 1 82.2587 0.03279 1 80.7079 0.03598
19 1 83.2418 0.0331 1 81.7182 0.0362
20 1 84.1996 0.03342 1 82.7036 0.03643
21 1 85.1348 0.03376 1 83.6654 0.03666
22 1 86.0477 0.0341 1 84.604 0.03688
23 1 86.941 0.03445 1 85.5202 0.03711
24 1 87.8161 0.03479 1 86.4153 0.03734

WHO: Head circumference for age

The CDC 2000 charts carry no head-circumference reference past 36 months and this site does not use the CDC infant head-circumference chart at all, so head circumference stays on the WHO standard across the whole 0 to 60 month range. Granularity: one row per completed month of age, 0 through 60 months

WHO Child Growth Standards (2007 head circumference release), head-circumference-for-age, published L, M and S values in cm. Source file https://www.who.int/tools/child-growth-standards/standards/head-circumference-for-age, verified 2026-08-28
Age (months) Boys L Boys M Boys S Girls L Girls M Girls S
0 1 34.4618 0.03686 1 33.8787 0.03496
1 1 37.2759 0.03133 1 36.5463 0.0321
2 1 39.1285 0.02997 1 38.2521 0.03168
3 1 40.5135 0.02918 1 39.5328 0.0314
4 1 41.6317 0.02868 1 40.5817 0.03119
5 1 42.5576 0.02837 1 41.459 0.03102
6 1 43.3306 0.02817 1 42.1995 0.03087
7 1 43.9803 0.02804 1 42.829 0.03075
8 1 44.53 0.02796 1 43.3671 0.03063
9 1 44.9998 0.02792 1 43.83 0.03053
10 1 45.4051 0.0279 1 44.2319 0.03044
11 1 45.7573 0.02789 1 44.5844 0.03035
12 1 46.0661 0.02789 1 44.8965 0.03027
13 1 46.3395 0.02789 1 45.1752 0.03019
14 1 46.5844 0.02791 1 45.4265 0.03012
15 1 46.806 0.02792 1 45.6551 0.03006
16 1 47.0088 0.02795 1 45.865 0.02999
17 1 47.1962 0.02797 1 46.0598 0.02993
18 1 47.3711 0.028 1 46.2424 0.02987
19 1 47.5357 0.02803 1 46.4152 0.02982
20 1 47.6919 0.02806 1 46.5801 0.02977
21 1 47.8408 0.0281 1 46.7384 0.02972
22 1 47.9833 0.02813 1 46.8913 0.02967
23 1 48.1201 0.02817 1 47.0391 0.02962
24 1 48.2515 0.02821 1 47.1822 0.02957
25 1 48.3777 0.02825 1 47.3204 0.02953
26 1 48.4989 0.0283 1 47.4536 0.02949
27 1 48.6151 0.02834 1 47.5817 0.02945
28 1 48.7264 0.02838 1 47.7045 0.02941
29 1 48.8331 0.02842 1 47.8219 0.02937
30 1 48.9351 0.02847 1 47.934 0.02933
31 1 49.0327 0.02851 1 48.041 0.02929
32 1 49.126 0.02855 1 48.1432 0.02926
33 1 49.2153 0.02859 1 48.2408 0.02922
34 1 49.3007 0.02863 1 48.3343 0.02919
35 1 49.3826 0.02867 1 48.4239 0.02915
36 1 49.4612 0.02871 1 48.5099 0.02912
37 1 49.5367 0.02875 1 48.5926 0.02909
38 1 49.6093 0.02878 1 48.6722 0.02906
39 1 49.6791 0.02882 1 48.7489 0.02903
40 1 49.7465 0.02886 1 48.8228 0.029
41 1 49.8116 0.02889 1 48.8941 0.02897
42 1 49.8745 0.02893 1 48.9629 0.02894
43 1 49.9354 0.02896 1 49.0294 0.02891
44 1 49.9942 0.02899 1 49.0937 0.02888
45 1 50.0512 0.02903 1 49.156 0.02886
46 1 50.1064 0.02906 1 49.2164 0.02883
47 1 50.1598 0.02909 1 49.2751 0.0288
48 1 50.2115 0.02912 1 49.3321 0.02878
49 1 50.2617 0.02915 1 49.3877 0.02875
50 1 50.3105 0.02918 1 49.4419 0.02873
51 1 50.3578 0.02921 1 49.4947 0.0287
52 1 50.4039 0.02924 1 49.5464 0.02868
53 1 50.4488 0.02927 1 49.5969 0.02865
54 1 50.4926 0.02929 1 49.6464 0.02863
55 1 50.5354 0.02932 1 49.6947 0.02861
56 1 50.5772 0.02935 1 49.7421 0.02859
57 1 50.6183 0.02938 1 49.7885 0.02856
58 1 50.6587 0.0294 1 49.8341 0.02854
59 1 50.6984 0.02943 1 49.8789 0.02852
60 1 50.7375 0.02946 1 49.9229 0.0285

CDC: Weight for age

This is the 2 to 20 year CDC file. The separate CDC birth-to-36-month infant file is deliberately NOT used anywhere on this site: below 24 months this site uses the WHO standard, per the CDC and AAP recommendation. Granularity: the published CDC age grid: 24.0 months, then half-month midpoints (24.5, 25.5, ... 60.5). L, M and S at ages between grid points are linearly interpolated, which is how the CDC's own worked examples treat this file.

CDC 2000 Growth Charts, weight-for-age (2 to 20 years), published L, M and S values in kg. Source file https://www.cdc.gov/growthcharts/data/zscore/wtage.csv, verified 2026-08-28
Age (months) Boys L Boys M Boys S Girls L Girls M Girls S
24 -0.20615 12.67076 0.108126 -0.73534 12.05504 0.107399
24.5 -0.2165 12.74154 0.108166 -0.75221 12.13456 0.10774
25.5 -0.23979 12.88102 0.108275 -0.78423 12.29102 0.108477
26.5 -0.26632 13.01842 0.108421 -0.8141 12.44469 0.109281
27.5 -0.29575 13.1545 0.108605 -0.84194 12.59622 0.110144
28.5 -0.32773 13.2899 0.108826 -0.86789 12.74621 0.111061
29.5 -0.36182 13.42519 0.109083 -0.8921 12.89517 0.112023
30.5 -0.39757 13.56088 0.109378 -0.91472 13.04357 0.113023
31.5 -0.43452 13.69738 0.109708 -0.93588 13.19181 0.114056
32.5 -0.47219 13.83505 0.110073 -0.95572 13.34023 0.115115
33.5 -0.51012 13.97418 0.110473 -0.97438 13.48913 0.116193
34.5 -0.54789 14.11503 0.110907 -0.99198 13.63877 0.117286
35.5 -0.58507 14.2578 0.111375 -1.00864 13.78937 0.118387
36.5 -0.62132 14.40263 0.111875 -1.02447 13.94108 0.119492
37.5 -0.6563 14.54965 0.112406 -1.03957 14.09407 0.120596
38.5 -0.68974 14.69893 0.112967 -1.05404 14.24844 0.121695
39.5 -0.72141 14.85054 0.113558 -1.06795 14.40429 0.122785
40.5 -0.75118 15.00449 0.114177 -1.08137 14.56168 0.123863
41.5 -0.7789 15.16078 0.114822 -1.09438 14.72064 0.124927
42.5 -0.80452 15.3194 0.115493 -1.10702 14.88121 0.125973
43.5 -0.828 15.4803 0.116188 -1.11934 15.04341 0.127
44.5 -0.84938 15.64343 0.116904 -1.13137 15.20721 0.128006
45.5 -0.8687 15.80873 0.117641 -1.14314 15.37263 0.12899
46.5 -0.88603 15.9761 0.118397 -1.15466 15.53962 0.129951
47.5 -0.90151 16.14548 0.119169 -1.16596 15.70817 0.130889
48.5 -0.91524 16.31677 0.119955 -1.17703 15.87824 0.131802
49.5 -0.92738 16.48986 0.120755 -1.18787 16.04978 0.132692
50.5 -0.93807 16.66468 0.121565 -1.19848 16.22277 0.133559
51.5 -0.94748 16.8411 0.122385 -1.20885 16.39715 0.134403
52.5 -0.95577 17.01904 0.123212 -1.21897 16.57289 0.135226
53.5 -0.9631 17.19839 0.124044 -1.2288 16.74994 0.136028
54.5 -0.96963 17.37906 0.124879 -1.23833 16.92827 0.136811
55.5 -0.97553 17.56096 0.125716 -1.24754 17.10783 0.137576
56.5 -0.98094 17.744 0.126554 -1.25639 17.28859 0.138324
57.5 -0.98601 17.92809 0.12739 -1.26486 17.47052 0.139058
58.5 -0.99087 18.11316 0.128224 -1.27293 17.65361 0.139779
59.5 -0.99564 18.29912 0.129054 -1.28055 17.83782 0.14049
60.5 -1.00045 18.48592 0.129879 -1.28769 18.02314 0.141191

CDC: Length or height for age

Stature means standing height. The CDC stature-for-age reference starts at 24 months because that is the age at which children are measured standing rather than lying down. Granularity: the published CDC age grid: 24.0 months, then half-month midpoints (24.5, 25.5, ... 60.5). L, M and S at ages between grid points are linearly interpolated, which is how the CDC's own worked examples treat this file.

CDC 2000 Growth Charts, stature-for-age (2 to 20 years), published L, M and S values in cm. Source file https://www.cdc.gov/growthcharts/data/zscore/statage.csv, verified 2026-08-28
Age (months) Boys L Boys M Boys S Girls L Girls M Girls S
24 0.94152 86.4522 0.040322 1.07245 84.97556 0.040791
24.5 1.00721 86.86161 0.040396 1.05127 85.39732 0.04086
25.5 0.83725 87.65247 0.040578 1.04195 86.29026 0.041142
26.5 0.68149 88.42326 0.040723 1.01259 87.15714 0.041349
27.5 0.53878 89.17549 0.040833 0.97054 87.99602 0.0415
28.5 0.4077 89.91041 0.040909 0.92113 88.80551 0.041611
29.5 0.28676 90.62908 0.040952 0.86822 89.58477 0.041692
30.5 0.17449 91.33242 0.040965 0.81454 90.33342 0.041754
31.5 0.06944 92.02127 0.04095 0.76196 91.05154 0.041804
32.5 -0.02972 92.69638 0.040909 0.71166 91.73964 0.041847
33.5 -0.12425 93.35847 0.040844 0.66432 92.39854 0.041888
34.5 -0.21529 94.00823 0.040758 0.62029 93.02945 0.041929
35.5 -0.30385 94.64637 0.040654 0.57956 93.63382 0.041972
36.5 -0.39092 95.27359 0.040534 0.54198 94.21336 0.042018
37.5 -0.2548 95.91475 0.040573 0.51143 94.79643 0.042105
38.5 -0.12565 96.54734 0.040617 0.4828 95.37392 0.0422
39.5 -0.00317 97.17191 0.040666 0.45552 95.94693 0.0423
40.5 0.11291 97.78898 0.040721 0.42915 96.51645 0.042405
41.5 0.22275 98.39903 0.040782 0.40335 97.08337 0.042513
42.5 0.32653 99.00254 0.040848 0.37788 97.64848 0.042622
43.5 0.42436 99.59998 0.040919 0.35256 98.21247 0.042731
44.5 0.51635 100.19176 0.040996 0.32727 98.77593 0.04284
45.5 0.6026 100.77832 0.041076 0.30196 99.3394 0.042947
46.5 0.68317 101.36004 0.041162 0.27658 99.90331 0.043054
47.5 0.75816 101.93731 0.041251 0.25116 100.46805 0.043158
48.5 0.82764 102.51047 0.041344 0.22571 101.03393 0.04326
49.5 0.89169 103.07989 0.041441 0.20027 101.60119 0.043359
50.5 0.95039 103.64586 0.04154 0.17491 102.17004 0.043456
51.5 1.00383 104.20871 0.041641 0.1497 102.74061 0.043551
52.5 1.05214 104.76873 0.041745 0.12471 103.31301 0.043642
53.5 1.09537 105.32616 0.04185 0.10001 103.88728 0.043731
54.5 1.13365 105.88128 0.041956 0.0757 104.46345 0.043817
55.5 1.1671 106.43431 0.042063 0.05185 105.04149 0.0439
56.5 1.19585 106.98548 0.04217 0.02854 105.62133 0.04398
57.5 1.22 107.53497 0.042277 0.00585 106.20289 0.044058
58.5 1.23972 108.08297 0.042383 -0.01613 106.78606 0.044133
59.5 1.25512 108.62965 0.042489 -0.03735 107.37068 0.044206
60.5 1.26637 109.17514 0.042593 -0.05773 107.9566 0.044277

Limitations

  • These are reference curves, not measurements of your child or of children near you. A percentile locates a value inside the published reference population and says nothing about health.
  • The WHO tables here are published at whole months of age. The CDC file is published at 24.0 months and then at half-month midpoints. Between published rows this site interpolates L, M and S linearly, which introduces a small error at ages that fall between two rows.
  • WHO also publishes day-by-day expanded tables. This site uses the monthly tables, which is enough resolution for a chart read by eye and keeps the page small enough to load on a phone.
  • The WHO and CDC curves are fitted to different populations and do not meet at 24 months. The step is shown, never smoothed away, so a value read on one side of the seam is not directly comparable to a value read on the other.
  • The CDC's separate birth-to-36-month infant data file is deliberately not used anywhere on this site, at any age.
  • Percentile values in the milestone table are computed from the published L, M and S, so they can differ in the last decimal place from the rounded percentile columns the agencies print alongside those parameters.

Percentiles describe position in a reference population, not health. Growth patterns are for your pediatrician to read.

Update history

  • WHO WHO Child Growth Standards (2006), weight-for-age downloaded from the agency and reproduced in full, 25 age rows per sex.
  • WHO WHO Child Growth Standards (2006), length-for-age (recumbent length, 0 to 24 months) downloaded from the agency and reproduced in full, 25 age rows per sex.
  • WHO WHO Child Growth Standards (2007 head circumference release), head-circumference-for-age downloaded from the agency and reproduced in full, 61 age rows per sex.
  • CDC CDC 2000 Growth Charts, weight-for-age (2 to 20 years) downloaded from the agency and reproduced in full, 38 age rows per sex.
  • CDC CDC 2000 Growth Charts, stature-for-age (2 to 20 years) downloaded from the agency and reproduced in full, 38 age rows per sex.

Verified 2026-08-28. Every row on this page traces to one of the five files listed above; if a figure here does not match the agency file, the agency file is right and this page is wrong. The methodology page explains how corrections are handled.