I. NATURE OF CASE
In this dissolution action, the husband is the cofounder and president of a C corporation and owns 34 percent of its stock. He asserts that only the appreciation, during the marriage, of a business interest that is due to the active efforts of the nonowning spouse is part of the marital estate. He claims, therefore, that none of the almost $5 million in appreciation of his stock interest during the parties' 25-year marriage was subject to equitable division.
Janet E. Stephens and Robert L. Stephens were married on September 8, 1991. Twin boys were born of the marriage in 1996. Robert filed for dissolution in 2014.
For approximately 15 years of the marriage, Janet worked as a real estate agent. But during the last 10 years of the marriage, Janet suffered from a mental illness that required periodic hospitalization and left her unable to work. She receives approximately $1,500 per month in Social Security disability income. Robert testified that he did not expect Janet would recover and become employable in the future.
A guardian ad litem (GAL) was appointed to protect Janet's interests at trial. The GAL is also Janet's guardian and conservator. Janet refused to participate in the dissolution proceedings but was represented by counsel.
Both before and during the marriage, Robert worked full time as president of Stephens & Smith Construction Co., Inc. (Stephens & Smith), and his current annual salary is approximately $265,000 per year. Robert received additional income from bonuses and from his other business interests. In 2014, Robert's total taxable income was $503,414. When Janet's mental health allowed, she shared equally with Robert the tasks relating to the care of their children.
The principal issue at trial was what assets should be considered marital and subject to equitable division. The approximate total value of the assets under the court's consideration in the dissolution action was $9 million. There were 166 exhibits entered into evidence without objection, and Robert was the only witness.
1. STEPHENS & SMITH
Stephens & Smith is a construction company specializing in concrete work. At all relevant times before and during the marriage, Robert owned stock totaling 34 percent of the stock of Stephens & Smith. Robert cofounded Stephens & Smith in 1971 as a partnership with Michael Smith. Stephens & Smith was incorporated as a C corporation in 1974. According to the exhibits in the record, Robert's stock in Stephens & Smith was worth $298,459 in 1991 before the parties married. Robert's stock in Stephens & Smith at the time of dissolution was worth $5,044,934.16.
Robert worked a "normal eight-hour day," 5 days a week, in his capacity as president. At other times during the marriage, he worked more. He was also on the 12-member board of directors. Robert admitted that he sets his own salary and has a significant role in determining bonuses.
Robert testified that the leadership personnel of Stephens & Smith has not changed since the marriage. He described Stephens & Smith as consisting of six moneymaking departments, each with its own department head. Robert was involved in selecting and training the leadership within Stephens & Smith. At all times during the marriage, Stephens & Smith had approximately 200 employees. Robert considered at least 20 of those employees "integral," though he believed every employee was important.
Robert described his role as president as "constantly changing." He made financial and investment decisions for Stephens & Smith and performed "some management real estate oversight." As part of obtaining lending to fund Stephens & Smith's projects, Robert also personally guaranteed millions of dollars in loans for Stephens & Smith's operations.
Robert attended human resources, rental management, shareholder, and board meetings. He occasionally consulted with and advised the department heads for the company. Robert conceded that he was an integral part of the success of Stephens & Smith. But Robert suggested that, based on his latest bonus of 6 percent, "maybe I provide 6 percent of the leadership."
2. R.I.P., INC.
R.I.P., Inc., is a wholly owned subsidiary of Stephens & Smith. It holds Stephens & Smith's real estate investments and represents approximately two-thirds of Stephens & Smith's value. R.I.P. was created before the marriage with capital from Stephens & Smith, and continued thereafter to be funded by the profits of Stephens & Smith. R.I.P. owns a percentage of The Mystic Pines Apartments, L.L.C.; Eagles Landing Apartments, LLC; Aardvark Antique Mall, LLC; and Village Square Apartments, LLC. Although there was no testimony specifically on this point, Robert's estimated interest in Stephens & Smith of $5,044,934.16 apparently includes any interests held through R.I.P.
3. INFINITY S DEVELOPMENT CO., HERITAGE SQUARE PARTNERS, SMITH AND STEPHENS REAL ESTATE, AND AARDVARK PARTNERS
(a) Infinity S Development
Infinity S Development Co. (Infinity) is a partnership between Robert, Smith, and one other partner. Infinity is predominantly involved in the self-storage business, and at the time of trial, it owned approximately 900 storage units. At one point, Robert testified that no capital has been added to Infinity since the marriage. Its expansion has been paid for with the partnership's profits. Robert also indicated, however, that as with Stephens & Smith, he had personally guaranteed bank loans to Infinity.
The day-to-day operation of Infinity is run by a hired manager. But Robert and the two other partners make the larger decisions, such as what to build. Robert participates in monthly meetings to analyze occupancy rates and financial statements. Robert owns one-fourth of Infinity. According to the exhibits in evidence, at the time of trial, Robert's equity interest in Infinity was $1,243,232. In contrast, when the parties married, Robert's interest in Infinity was worth $270,553.
(b) Heritage Square Partners
Heritage Square Partners (Heritage) was formed as an offshoot of Infinity just prior to the marriage. The partnership consists of Robert; Smith; and, originally, three other persons. It owns one building that was capitalized with funds from Infinity and with loans. No other funds have been funneled into Heritage since the marriage. The building provides rental income and is managed by a person employed by the partnership. Robert is not involved in the day-to-day operation of Heritage. At the time of trial, Robert's equity interest in Heritage was $403,884. It was unclear what the value of Robert's interest in Heritage was at the time the parties married.
(c) Smith and Stephens Real Estate
Smith and Stephens Real Estate was created by Robert and Smith before the marriage and owns a single piece of property that was purchased before the marriage. The value of Robert's interest in Smith and Stephens Real Estate when the parties married was $88,830, and it was $140,000 at the time of trial.
(d) Aardvark Partners
Aardvark Partners, LLC, was formed after the marriage. It was formed by the five partners of Infinity and with R.I.P. as the sixth partner. R.I.P. owns 50 percent of Aardvark Partners. The $500,000 purchase of the real estate held by Aardvark Partners was capitalized with $50,000 from each of five individual investor partners from Infinity and $250,000 from R.I.P. Each individual obtained the $50,000 contribution through a distribution of $55,000 from Infinity.
Aardvark Partners owns a property that consists of a cluster of buildings and parking lots. Robert is not involved in the day-to-day operation of Aardvark Partners, which is run by a hired manager. At the time of trial, Robert's interest in Aardvark Partners was valued at $306,429.
4. AARDVARK ANTIQUE MALL, THE MYSTIC PINES APARTMENTS, AND EAGLES LANDING APARTMENTS
Robert conceded at trial that his ownership interests in Aardvark Antique Mall, The Mystic Pines Apartments, and Eagles Landing Apartments were marital property. At the time of trial, Aardvark Antique Mall was valued at $66,474, The Mystic Pines Apartments were valued at $923,687, and Eagles Landing Apartments were valued at $381,385. Robert's combined interest in the three properties produced approximately $60,000 per year in owner draws, and he proposed that it would be most beneficial for all parties to transfer to Janet the ownership interest in these properties.
Janet's attorney and GAL questioned the practicality of making Janet part-owner of the properties. Janet's counsel also pointed out that transfer of ownership would require the cooperation of the other partners, since at least two of the entities required owner approval before allowing new members. Robert assured the court that the partners having an interest in these properties would cooperate.
The court awarded to Robert the marital home, valued at $542,000, and the mortgage debt therein, in the amount of $337,078. Also awarded to Robert, subject to liens or encumbrances, were a "60-foot Gen[i]e Manlift" valued at $20,000, a jet ski valued at $1,740, a 1998 motorcycle valued at $7,625, a 2003 automobile valued at $16,904, and a 2005 recreation vehicle valued at $60,250. The only debt associated with these items appears to be an automobile loan in the amount of $19,893.
Robert was awarded $31,965 in household goods and artwork. Robert was awarded a credit union checking account with a balance of $553.50 and a bank checking account with a balance of $100. Robert was awarded Stephens & Smith retirement plans valued at $326,104.79. The retirement plans were formed after the marriage, and Robert had conceded they were marital assets.
Robert was solely responsible for a personal loan in 2009 from his sister in the amount of $480,589, for the purpose of investing in Eagles Landing Apartments and The Mystic Pines Apartments. Robert was awarded any and all bank or investment accounts, life insurance policies and annuities, and any household goods or personal property in his possession not otherwise allocated.
The court awarded to Janet, along with any indebtedness thereon, a 2012 automobile valued at $27,357. The court awarded to Janet $18,510 in household goods and artwork, any and all jewelry, including a $10,000 ring that Janet had purportedly flushed down the toilet. It was unclear to what extent the other jewelry could be located at the time of trial. The jewelry, minus the ring, was appraised at $72,760. Janet was awarded an account at a local bank with a balance at the time of trial of $10,010. She was awarded any and all bank or investment accounts, life insurance policies and annuities, and any household goods or personal property in her possession not otherwise allocated.
The court found that Robert's combined interest in Aardvark Antique Mall ($66,474), The Mystic Pines Apartments ($923,687), and Eagles Landing Apartments ($381,385) was part of the marital estate. In light of the tax disadvantages of the forced buying or selling of the business interests, and the court's trust that Robert would conduct his business affairs so as not to disadvantage Janet, the court awarded Robert and Janet each one-half of the total interest in these properties through a transfer of ownership. Robert was ordered to complete all documentation of such joint ownership within 30 days of the decree.
The court found that Robert's ownership interests in Infinity, Heritage, Smith and Stephens Real Estate, and Aardvark Partners were traceable to premarital assets and that the entirety of the appreciation in value of these interests during the marriage was excludable from the marital estate, because Robert had a "passive" role in such appreciation. It noted that no marital assets and no active effort by Janet contributed to these entities. The court awarded these interests in their entirety to Robert.
The court also found that Robert's 34 percent ownership interest in Stephens & Smith was, in its entirety, nonmarital. It did not specifically mention R.I.P. in its decree, which was presumably treated as part of Stephens & Smith.
The court noted that no marital funds were contributed to Stephens & Smith. And, as for the substantial appreciation of the company's value during the marriage, the court cited Van Newkirk v. Van Newkirk
Although the court concluded that the entirety of Stephens & Smith was nonmarital property, it nevertheless awarded a "Grace award"
Other marital property, a coin collection and various items held in storage units, had not yet been given an estimated value and were ordered divided by equal value or sold with the proceeds to be divided equally between Robert and Janet.
The court found that Janet was suffering from a mental illness as defined by Neb. Rev. Stat. § 42-362 (Reissue 2016) and awarded alimony under § 42-362 in the amount of $1,000 per month for 120 months. It ordered Robert to maintain until August 20, 2020, a life insurance policy in the amount of $1 million, with Janet as the beneficiary.
Janet appeals from the decree. Robert did not cross-appeal.
III. ASSIGNMENTS OF ERROR
Janet assigns that the district court erred in (1) finding that the appreciation in the value of Stephens & Smith during the parties' marriage should be considered nonmarital, (2) failing to find that the spousal support ordered under § 42-362 should continue until Janet's mental disability is corrected, and (3) ordering the division of marital property held in a small business or partnership when the articles of organization do not allow for the same.
IV. STANDARD OF REVIEW
[1,2] In actions for dissolution of marriage, an appellate court reviews the case de novo on the record to determine whether there has been an abuse of discretion by the trial judge.
1. PROPERTY DIVISION
 Janet first assigns as error the district court's finding that the appreciation during the parties' marriage of Robert's interest in Stephens & Smith should be considered nonmarital. She does not assign as error the court's determination that other assets at issue at trial were nonmarital. Errors must be specifically assigned and argued to be considered by an appellate court.
Thus, we consider only whether the district court erred in its classification of Stephens & Smith, together with its wholly owned subsidiary, R.I.P.—which we hereafter refer to collectively as "Stephens & Smith." We do not consider whether the court erred with respect to its classification of Infinity, Heritage, Smith and Stephens Real Estate, or Aardvark Partners as nonmarital assets. And because Robert did not cross-appeal, neither do we consider whether the court erred in designating Aardvark Antique Mall, The Mystic Pines Apartments, and Eagles Landing Apartments as marital. We do consider the propriety of the "Grace award," as it is inseparable from the court's determination that Stephens & Smith was nonmarital.
Neb. Rev. Stat. § 42-365 (Reissue 2016) provides that when a dissolution of marriage is decreed, the court may order the
Section 42-365 provides that "[t]he purpose of a property division is to distribute the marital assets equitably between the parties." (Emphasis supplied.)
No statute defines "marital assets." Neb. Rev. Stat. § 42-366(8) (Reissue 2016) states that in the event the parties fail to agree upon a property settlement that is conscionable, the court shall order the equitable division of the marital estate, which "shall include . . . any pension plans, retirement plans, annuities, and other deferred compensation benefits owned by either party, whether vested or not vested." But no statutory provision relating to the equitable division of property specifically addresses business entities or the concept of appreciation.
 We find no merit to Robert's argument that § 42-366 is a legislative mandate to exclude from the marital estate items not specifically listed in § 42-366. Traditionally, the word "include" in a statute connotes that the provided list of components is not exhaustive and that there are other items includable though not specifically enumerated.
 Since 2000, we classify as a threshold matter the parties' property as either marital or nonmarital. In Meints v. Meints,
Such division between the marital and nonmarital estate is known as dual classification. Prior to Meints, our case law was not entirely clear as to whether we operated under a dual classification system. Most jurisdictions adopt the dual classification model and preclude under this model the equitable distribution of separate property.
[6,7] We have said that all property accumulated and acquired by either spouse during the marriage is part of the marital estate, unless it falls within an exception to this general rule.
 In the recent case of Stanosheck v. Jeanette,
[9-11] Other jurisdictions have reached a "remarkable degree of consensus" that appreciation or income of separate property is marital property to the extent that it was caused by marital funds or marital efforts.
Robert, however, argues that Stanosheck and Coufal, inasmuch as they recognize as marital property growth due to the efforts of the owning spouse, are limited to retirement accounts. He argues that appreciation of business interests outside of retirement accounts should be considered a marital asset only if the appreciation during the marriage was caused by the efforts of the nonowning spouse.
In support of this position, Robert relies on statements by this court in cases decided before we clearly adopted a dual classification system
But in Rezac v. Rezac,
We observed in Rezac that the lower court was correct in treating the appreciation of stock as marital property, because the corporation had paid for substantial improvements that increased the corporate value, in lieu of distributing profits to its owners as income. We explained that "had the corporation not made substantial investments in improving its facility, the value of the stock may have remained about the same but this respondent would have received additional income resulting in marital assets which would be subject to division at the time of the dissolution."
Though we observed in Rezac that the appreciation was through reinvestment of income, other courts and legal authorities find no meaningful distinction between appreciation through reinvestment of income and appreciation through active efforts other than reinvestment.
Nevertheless, in Grace v. Grace,
In Grace, we applied our statement in Van Newkirk to hold that the husband's interest in a premarital family business was nonmarital. Then we said that whether an asset is marital is but one consideration in the equitable division of property.
A series of cases from the Nebraska Court of Appeals have since recognized so-called Grace awards in order to achieve an equitable result when the application of our statement in Van Newkirk renders appreciation during the marriage nonmarital.
We find inapplicable to the modern dual classification system any statements in Van Newkirk and its progeny which fail to recognize as a marital asset appreciation through the active efforts of the owning spouse. For purposes of the active appreciation rule, there is no reason to treat appreciation of a nonmarital asset differently from income derived from a nonmarital asset during the marriage. We conclude, likewise, that the principles set forth in Grace are no longer applicable to the dual classification system set forth by this court in Meints v. Meints.
 We hold, therefore, that the principles set forth in Stanosheck apply equally to appreciation or income during the marriage of any nonmarital asset. Thus, accrued investment earnings or appreciation of nonmarital assets during the marriage are presumed marital unless the party seeking the classification of the growth as nonmarital proves: (1) The growth is readily identifiable and traceable to the nonmarital portion of the account and (2) the growth is not due to the active efforts of either spouse.
 We expressly adopt the active appreciation rule that does not distinguish between the efforts of the owning spouse and the efforts of the nonowning spouse. We agree that the majority rule recognizing as a marital contribution the efforts of either the owning or the nonowning spouse is "clearly correct, as the marital estate should include the fruits of either spouse's efforts during the marriage."
Under the district court's interpretation of our admittedly confusing line of case law, it concluded that appreciation of Stephens & Smith due to Robert's active efforts was not includable in the marital estate. The court accordingly made no findings concerning what portion of Stephens & Smith's appreciation was attributable to Robert's active efforts. Because Janet did not directly contribute to Stephens & Smith, the court concluded that the entirety of Stephens & Smith's appreciation during the marriage was nonmarital. In its attempt to make an equitable distribution after having thus excluded approximately $5 million from the marital estate, the court awarded as a Grace award approximately one-fourth of Robert's 34-percent interest in Stephens & Smith.
Based upon the active appreciation rule, the court should not have excluded Stephens & Smith from the marital estate and substituted a Grace award. We reverse the court's determination of the marital property to the extent that it did not include the increase in value of Robert's interest in Stephens & Smith, and we vacate the court's Grace award.
The classification of the growth in value of Robert's stock, including that due to retained earnings by Stephens & Smith,
[14,15] Despite the importance of each employee in a company, a company's value for purposes of active appreciation is attributable only to the efforts of first-tier management or similar persons with control over the asset's value.
Even favorable market conditions are not passive inasmuch as they create merely the opportunity that the skilled, owning spouse detects and seizes.
 It was Robert's burden to demonstrate that any portion of Stephens & Smith's appreciation was due to passive forces or the active efforts of third parties who would qualify as firsttier management or similar. In presenting the evidence at trial, Robert was on notice of the possibility that the court would apply the active appreciation rule. And it has been the longstanding position of this court that the burden of proof to show that property is nonmarital remains with the person making the claim.
We accordingly direct the court to consider as marital the entirety of the increase during the marriage of Robert's 34-percent stock interest in Stephens & Smith. Because the district court is in the better position to make an equitable division, we remand the cause with directions to determine the equitable distribution of that marital asset.
2. SPOUSAL SUPPORT
We turn next to Janet's allegation that the district court erred in failing to award spousal support under § 42-362 for so long as she remains mentally ill. Janet does not take issue with the monthly amount that was awarded, only its duration.
Section 42-362 states in relevant part:
 The amount of support awarded under § 42-362 is a matter initially entrusted to the sound discretion of the trial judge, which award, on appeal to this court, is reviewed de novo on the record and affirmed in the absence of an abuse of the trial judge's discretion.
Section 42-362 empowers the court to order the payment of such support and maintenance "`as it may deem necessary and proper, having due regard to the property and income of the parties'" and, to that extent, parallels the alimony contemplated by § 42-365, but provides an additional specific ground to be considered—the mental illness of a spouse.
However, support and maintenance of a mentally ill spouse and alimony are not the same in all respects.
We have never held that a court must always award support under § 42-362 for so long as the mental illness continues. Nothing in the language of the statute indicates this is required. Rather, § 42-362 contemplates that the order of support under this section "may, if necessary, be revised from time to time on like application." We find that the district court did not abuse its discretion in making the award for 120 months. Because of our determination that Stephens & Smith is a marital asset, the court in its discretion may reconsider the amount of alimony.
3. ARTICLES OF INCORPORATION
Janet last assigns as error the fact that the court ordered the transfer to her of ownership interests in Aardvark Antique Mall, The Mystic Pines Apartments, and Eagles Landing Apartments, instead of a cash award. Janet's sole objection is her concern that the other partners will not consent to her co-ownership. Robert was ordered to complete all documentation of such joint ownership within 30 days of the decree. In the event that did not occur, and it appears that a transfer of ownership will not take place in spite of Robert's best efforts, then the parties are free to seek modification of the decree.
We affirm the distribution of ownership interests in Aardvark Antique Mall, The Mystic Pines Apartments, and Eagles Landing Apartments, instead of a cash award. We reverse the division of the property described as Stephens & Smith and direct the court to include the increase in value from the date of the marriage to the dissolution as a marital asset. The Grace award is reversed and vacated, because the court is directed to include the increase in value of Robert's interest in Stephens & Smith as a marital asset. We affirm the award of alimony subject to the court's discretion as set forth in this opinion.
AFFIRMED IN PART, VACATED IN PART, AND IN PART REVERSED AND REMANDED WITH DIRECTIONS.
STACY, J., not participating.