Selection from the list of topics

Estimates and standard error of the estimates

The results published in the NFI tables are estimates for variables in the Swiss forest (population parameters) whose true values are not known and must therefore be extrapolated (estimated) from the NFI sample data.

The extrapolations carry uncertainties. However, the accuracy of the extrapolations can be reliably estimated from the NFI sample, which is designed to be a random sample. To this end, all NFI tables include a second figure in addition to the estimate itself, namely the standard error of the estimate.

In most tables the percent standard error is reported (±%), but the absolute standard error (±) is also reported occasionally, especially for estimated percentages. The relationship between absolute and percent standard error is as follows:

percent standard error = absolute standard error / estimate × 100

absolute standard error = percent standard error × estimate / 100

Information on the forest road network is based on a full survey of all forest roads. In this case, there is no need to specify a standard error because there is no uncertainty caused by sampling.

Confidence interval of the estimate

With the estimate and the standard error of the estimate, the limits of the so-called confidence interval of the estimate can be calculated as:

lower limit = estimate – tQ × absolute standard error

upper limit = estimate + tQ × absolute standard error

If the simple standard error is used for the calculation (tQ = 1), then the 68% confidence interval is formed. In this case, the true value of the population parameter has a 68% probability of lying within this confidence interval of the estimate. If the double standard error is used (tQ = 2), then there is a 95% probability that the true value lies within this 95% confidence interval.

Significance of the estimate

The confidence interval can be used to statistically test whether the estimated population parameter is larger or smaller than a specific reference or target value, or whether two estimated population parameters truly differ (in the real population). For practical applications, proceed as follows: if a reference value lies outside the confidence interval, the estimated population value can be interpreted as being significantly different from it; if it lies within the confidence interval, the difference between the estimated population parameter and the reference value can be interpreted as random or not significant. When two population parameters are compared, they can be interpreted as differing significantly if their confidence intervals do not overlap.

Dealing with missing values

When calculating a results table, data are not always available for all combinations of characteristics^* of the classification variables and regional demarcation applied. In most cases, this indicates that the attribute estimated with the respective target variable does not occur or occurs only very rarely. Usually, the value 0 is used (imputed). However, as this value is not based on direct measurements, the associated standard error is represented with a full stop [.]. If the imputed value of 0 is referred to in the calculation, e.g. in the case of percentages or certain change estimates, no value can be entered. In this case, the estimated value and standard error are both represented with a full stop [.].

For example, no Arolla pines have been found and measured in the Swiss Plateau to date (growing stock of Arolla pines by production region). The values can be assumed to be missing because Arolla pine does not occur in the Swiss Plateau and therefore the growing stock there must be 0.

^* e.g. ‘Arolla pine’ characteristic of the classification variable ‘tree species’ and ‘Swiss plateau’ characteristic of the ‘regional demarcation’

Changes

There are two types of changes in the NFI:

The first type involves specific target variables relating to components of change, such as increment, fellings, mortality and losses. These target variables are only available for two consecutive inventory cycles, e.g. NFI3–NFI4. In the evaluation of components of change, the classification variable characteristic of the second inventory cycle is assigned to the first inventory cycle. These evaluations therefore do not take into account potential changes in a classification variable characteristic from the earlier to the later inventory (e.g. from private to public ownership).

With the second type of change, the difference in target variables, such as number of stems, growing stock or forest area, is used to assess the change between two inventory cycles. Target variables are generally used to represent states, such as that in NFI4, but can also indicate the net change between any two inventory cycles, e.g. NFI1–NFI4. In evaluations of change using these target variables, the change in a classification variable characteristic is considered in the analysis. Consequently, one can detect, for example, that the forest area without shrub forest increased between the two inventory cycles. This only has an effect on classification variables whose characteristic (class) can actually change, e.g. the affiliation with a forest area or the tree condition.

NFI5
total number of stems with two most important forms of damages
altitude (in 200 m classes) · cause of damage to trees (10 classes)
regional demarcation: economic region
unit: 1000 n
evaluation area: accessible forest without shrub forest NFI4/NFI5
grid: 1.4 km grid, subgrids 1-5
state 2018/26
		economic region
		Western Jura		Eastern Jura		Western Plateau		Central Plateau		Eastern Plateau		Western Pre-Alps		Central Pre-Alps		Eastern Pre-Alps		Northwestern Alps		Central Alps		Northeastern Alps		Southwestern Alps		Southeastern Alps		Southern Alps		Switzerland
altitude (in 200 m classes)	cause of damage to trees (10 classes)	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%
n/a	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	various	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	other human activity	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	weather	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	dead trees	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
>1800 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	0	.	0	.	0	.	0	.	0	.	496	100	69	100	0	.	769	50	255	100	71	100	5408	16	11320	12	3932	17	22320	8
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	7	100	7	100
	rockfall	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	325	27	154	43	343	53	823	26
	various	0	.	0	.	0	.	0	.	0	.	0	.	17	100	0	.	33	63	0	.	28	100	243	36	623	25	215	26	1159	17
	indeterminable	0	.	0	.	0	.	0	.	0	.	15	100	66	100	0	.	337	44	55	100	60	100	1991	19	4453	14	1481	18	8456	9
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	79	53	20	76	0	.	100	45
	other human activity	0	.	0	.	0	.	0	.	0	.	0	.	14	100	0	.	9	100	0	.	0	.	293	46	44	47	63	69	423	34
	weather	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	18	100	409	27	290	26	615	39	1332	21
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	122	62	452	39	93	49	667	29
	dead trees	0	.	0	.	0	.	0	.	0	.	0	.	222	100	0	.	237	53	18	100	0	.	1827	21	2918	17	876	29	6099	12
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1601-1800 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	0	.	0	.	0	.	0	.	0	.	764	51	2945	38	272	100	2360	23	262	48	1065	53	6651	18	8080	14	4793	18	27192	8
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	0	.	0	.	0	.	0	.	0	.	32	71	163	53	0	.	118	63	0	.	0	.	163	36	311	36	206	52	993	20
	various	0	.	0	.	0	.	0	.	0	.	16	71	146	44	0	.	229	63	154	84	24	77	196	30	424	29	339	34	1529	18
	indeterminable	0	.	0	.	0	.	0	.	0	.	313	62	656	35	0	.	946	27	290	50	117	48	2384	17	2766	15	1129	21	8601	9
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	55	100	0	.	0	.	7	100	41	46	27	100	130	50
	other human activity	0	.	0	.	0	.	0	.	0	.	8	100	37	100	0	.	35	61	0	.	7	100	227	52	222	40	43	61	579	27
	weather	0	.	0	.	0	.	0	.	0	.	0	.	62	62	0	.	144	43	0	.	24	77	453	42	310	33	260	25	1254	19
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	79	92	22	100	35	100	0	.	0	.	68	48	18	100	16	100	238	39
	dead trees	0	.	0	.	0	.	0	.	0	.	180	59	632	49	127	100	1042	36	93	58	96	54	2233	25	1334	18	600	25	6338	13
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1401-1600 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	680	34	0	.	386	53	0	.	0	.	2465	34	3260	22	1622	34	4402	19	1679	34	923	34	5872	17	9563	14	7386	17	38238	7
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	13	100	0	.	0	.	0	.	0	.	85	76	203	62	0	.	537	52	25	77	57	59	388	41	519	44	402	34	2227	20
	various	138	47	0	.	0	.	0	.	0	.	111	55	22	75	149	76	167	36	31	64	69	70	231	31	192	42	495	24	1605	14
	indeterminable	185	36	0	.	61	61	0	.	0	.	864	31	1263	21	195	39	1294	18	522	36	361	42	1685	19	2769	15	1504	19	10704	7
	wood harvest	8	100	0	.	0	.	0	.	0	.	15	72	42	100	7	100	48	55	37	100	0	.	37	56	131	42	18	100	342	26
	other human activity	0	.	0	.	0	.	0	.	0	.	143	64	102	62	15	100	93	53	71	100	0	.	172	47	199	37	42	71	838	22
	weather	26	78	0	.	0	.	0	.	0	.	43	48	125	42	12	100	166	38	134	63	25	76	313	32	279	29	402	26	1524	13
	lying living trees	0	.	0	.	0	.	0	.	0	.	37	72	0	.	0	.	18	100	58	100	104	71	198	60	88	53	84	59	586	29
	dead trees	51	54	0	.	134	84	0	.	0	.	930	34	901	30	607	55	1391	24	290	41	357	49	1532	21	2385	23	1436	21	10015	10
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1201-1400 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	5587	17	0	.	253	66	0	.	0	.	3892	21	3593	21	3225	19	3046	25	1935	29	1403	30	5748	19	3584	21	5141	18	37408	7
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	33	100	33	100
	rockfall	21	100	0	.	0	.	0	.	0	.	337	60	300	45	178	45	252	43	408	67	543	45	459	40	265	54	699	27	3461	16
	various	305	30	0	.	0	.	0	.	0	.	216	41	145	67	338	37	126	42	125	61	197	45	743	47	114	47	445	29	2754	16
	indeterminable	886	19	0	.	59	72	0	.	0	.	864	25	1247	22	800	22	824	24	450	32	503	32	931	23	1533	23	1468	18	9564	7
	wood harvest	111	44	0	.	0	.	0	.	0	.	37	60	43	62	74	83	77	74	0	.	118	55	0	.	109	45	60	50	629	21
	other human activity	83	41	0	.	0	.	0	.	0	.	260	52	19	100	136	49	23	75	7	100	0	.	18	100	159	49	26	76	730	24
	weather	253	45	0	.	7	100	0	.	0	.	150	42	119	37	36	83	98	56	131	71	107	48	101	51	186	47	340	28	1526	15
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	36	71	6	100	0	.	158	81	90	60	78	47	0	.	108	43	475	32
	dead trees	813	26	0	.	15	71	0	.	0	.	1105	26	1138	32	949	22	650	29	463	43	898	39	1331	22	1237	24	1133	24	9732	9
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1001-1200 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	12302	10	0	.	575	58	198	74	140	67	3456	24	7162	15	3920	18	2497	26	2075	29	1640	37	4041	19	2910	25	6343	17	47260	6
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	6	100	72	91	78	84
	rockfall	352	39	0	.	46	100	0	.	0	.	90	78	724	37	102	71	403	52	477	50	246	46	328	52	447	44	819	28	4032	14
	various	422	29	0	.	7	100	0	.	20	74	117	68	158	32	264	36	123	46	438	44	50	49	218	37	281	48	440	40	2538	14
	indeterminable	1664	13	0	.	76	92	7	100	7	100	721	33	1075	21	1056	21	464	26	462	30	507	34	886	26	1285	28	1633	19	9841	7
	wood harvest	742	20	0	.	0	.	0	.	23	100	101	59	309	33	273	38	7	100	22	100	135	54	7	100	33	81	7	100	1660	14
	other human activity	184	38	0	.	0	.	0	.	7	100	111	80	105	58	160	60	0	.	50	77	103	63	15	71	55	58	25	100	817	22
	weather	167	39	0	.	0	.	0	.	33	100	177	53	318	35	118	45	111	46	69	62	35	62	144	35	172	63	377	26	1721	14
	lying living trees	0	.	0	.	0	.	0	.	0	.	15	100	37	100	61	76	18	100	71	100	0	.	139	66	18	100	134	71	492	33
	dead trees	1487	18	0	.	59	75	34	100	0	.	690	29	1326	20	1211	31	551	37	537	36	394	43	1096	26	682	28	1217	25	9283	9
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
801-1000 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	11414	11	1445	31	1671	30	2445	30	1679	37	1971	31	8836	15	6994	16	2171	25	1208	39	918	31	2793	26	1987	27	6370	23	51901	6
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	1017	35	38	100	0	.	0	.	52	100	0	.	293	68	7	100	134	58	427	59	715	31	362	64	88	60	529	31	3662	17
	various	303	30	0	.	34	65	81	47	65	64	117	56	457	22	393	28	98	84	64	60	62	41	84	53	116	44	460	43	2333	13
	indeterminable	2106	16	201	41	275	39	301	31	301	36	387	34	1055	21	1185	21	446	35	232	45	364	35	762	28	804	29	1925	23	10343	8
	wood harvest	591	30	66	59	97	77	171	37	31	81	41	54	482	33	394	34	0	.	22	100	71	55	33	100	87	48	0	0	2087	14
	other human activity	252	38	19	100	0	.	8	100	82	82	39	81	235	53	188	40	26	76	18	100	19	100	7	100	50	74	69	48	1012	20
	weather	328	30	48	63	26	78	0	.	37	61	0	0	205	41	189	33	96	63	25	78	100	50	40	71	227	45	549	54	1870	19
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	94	55	0	.	8	100	18	100	22	77	18	100	18	100	204	58	382	35
	dead trees	1666	16	226	53	115	42	212	43	65	62	298	39	1496	23	1236	25	582	32	388	42	535	31	744	31	452	28	1882	24	9898	8
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
601-800 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	10686	13	2142	23	5283	21	9388	14	8036	13	923	46	5872	16	3857	22	1459	29	520	60	884	45	1196	46	2132	25	4541	19	56920	5
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	424	69	424	69
	rockfall	328	40	323	60	0	.	24	78	0	.	60	100	336	70	57	71	218	52	128	71	151	76	147	62	147	71	391	30	2310	18
	various	310	31	45	54	497	36	157	39	449	29	68	100	614	47	456	35	92	59	18	100	0	0	76	81	171	31	1238	40	4192	16
	indeterminable	1618	17	380	30	533	32	1321	21	1216	19	122	59	1023	21	1032	23	294	35	165	72	142	59	300	46	570	31	2052	20	10766	7
	wood harvest	507	24	125	46	280	39	706	22	563	24	0	.	402	32	75	51	32	100	6	100	17	73	0	.	33	100	90	100	2836	11
	other human activity	107	49	26	100	125	59	168	58	95	42	0	.	69	50	26	75	15	100	0	.	0	.	0	.	14	71	28	77	674	22
	weather	216	26	60	59	49	43	85	54	308	30	0	.	84	52	78	56	46	58	18	100	15	100	42	61	38	83	774	43	1812	20
	lying living trees	0	.	35	100	0	.	0	.	50	58	0	.	36	71	60	57	0	.	0	.	15	100	36	71	0	.	98	44	330	25
	dead trees	2169	16	425	36	544	26	797	24	859	23	153	77	829	29	882	27	357	35	0	.	299	41	477	37	413	35	2317	21	10522	8
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
=600 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	5212	16	8058	14	4042	19	11479	11	17454	8	0	.	699	56	994	38	648	62	896	48	102	74	1289	36	35	100	6550	18	57457	5
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	126	100	126	100
	rockfall	191	100	108	87	0	.	0	.	0	.	0	.	0	.	373	82	7	100	22	100	18	100	48	73	0	.	479	34	1247	33
	various	328	42	342	29	297	31	202	30	695	21	0	.	0	.	79	100	74	72	44	62	0	.	112	59	0	.	831	34	3003	13
	indeterminable	997	19	1356	16	579	24	963	17	3021	10	0	.	79	71	341	44	153	84	102	54	34	73	203	47	0	.	3027	18	10855	7
	wood harvest	281	29	342	31	128	39	980	21	1146	18	0	.	52	100	51	65	18	100	7	100	0	.	18	100	0	.	0	.	3025	11
	other human activity	54	58	142	37	96	49	129	41	253	64	0	.	0	.	36	65	0	0	16	100	0	.	75	100	0	.	192	41	994	22
	weather	204	35	232	30	150	48	84	39	425	23	0	.	0	.	70	68	44	72	18	100	0	.	36	71	0	.	430	28	1695	12
	lying living trees	62	53	90	44	0	.	0	.	97	41	0	.	0	.	21	74	15	100	0	.	0	.	18	100	0	.	323	41	627	24
	dead trees	1285	24	1356	19	851	28	725	20	1784	15	0	.	64	52	298	42	148	56	127	54	68	80	431	42	0	.	3335	17	10471	8
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
total	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	45881	4	11645	11	12211	12	23510	8	27309	6	13968	12	32437	7	20883	8	17351	9	8830	14	7005	15	32999	7	39610	6	45057	5	338696	2
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	6	100	662	50	669	49
	rockfall	1922	23	469	46	46	100	24	78	52	100	603	39	2018	22	717	45	1669	24	1486	30	1730	21	2219	18	1930	19	3868	11	18755	7
	various	1807	14	387	27	835	24	440	21	1229	16	646	25	1559	21	1679	17	943	22	873	28	430	26	1903	20	1922	14	4462	14	19114	5
	indeterminable	7457	6	1936	13	1583	16	2591	13	4544	9	3287	14	6465	9	4608	10	4757	10	2277	15	2087	16	9140	8	14179	7	14219	6	79131	2
	wood harvest	2241	12	533	24	505	28	1857	14	1764	14	194	35	1330	18	874	21	238	39	94	52	340	31	183	34	454	21	202	50	10809	5
	other human activity	680	20	188	33	220	40	305	36	436	41	562	33	581	28	562	25	203	31	162	52	129	53	806	26	744	20	489	22	6067	8
	weather	1194	15	340	24	232	34	169	33	803	17	370	31	912	18	503	22	704	19	394	35	324	25	1539	16	1502	15	3748	14	12735	6
	lying living trees	62	53	125	42	0	.	0	.	147	34	52	59	281	36	170	37	93	49	304	52	231	40	678	26	594	31	1060	21	3798	11
	dead trees	7472	8	2007	16	1717	17	1769	14	2708	12	3356	15	6610	11	5310	13	4958	13	1915	18	2647	18	9672	9	9421	9	12795	7	72357	3
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.

Table citation

Abegg, M.; Ahles, P.; Allgaier Leuch, B.; Cioldi, F.; Didion, M.; Düggelin, C.; Fischer, C.; Herold, A.; Meile, R.; Rohner, B.; Rösler, E.; Speich, S.; Temperli, C.; Traub, B.,
2023: Swiss national forest inventory - Result table No. 1346979. Birmensdorf, Swiss Federal Research Institute WSL

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